Extension

Extension version affected

Problem

Workaround

A9 Toolbar

All

Causes Unresponsive Script Warning

Uninstall A9 Toolbar

Adblock

All

Having the OBJ_TABS setting enabled may interfere with the Java, Flash or Windows Media Playerplugins. Content requiring these plugins may not display unless this setting is disabled.

If updating to Adblock 0.5.3.042 or later does not resolve the issue, keep the Adblock OBJ_TABS setting disabled.

Causes Google Gmail Chat to crash.

 ?

Adblock Plus

All ?

Can interfere with Flash content, most often on Mac OS.

Uncheck "Show Tabs on Flash and Java" in Adblock Plus options.

0.7.5.2

Windows error opening Internet shortcut or local HTML file - Firefox

Update to Adblock Plus version 0.7.5.3 or later

All-In-One Gestures

All versions using Firefox 2?

May cause Firefox crashes. Also conflicts reported with spellchecker in Linux Mac OSX versions.

All-In-One Sidebar

0.6.4 and prior

New extensions will not install. Also occurs in version 0.6.4 if updated from an earlier version or if used together with the SessionSaver extension.

Uninstall, then (re)install version 0.6.4. Disable opening the Extensions window in the sidebar (Misc. -> Extensions -> Open in Sidebar).

Amazing Media Browser

0.17

The "Block all embedded objects" preference is set to "Yes" by default, causing embedded media normally handled by plugins to disappear, including Flash content. Also interferes with the IE Tabextension.

Change the "Block all embedded objects" preference setting to "No".

Ask.com Toolbar 

Also available as:

Ask Toolbar for Firefox. May also be bundled with other software

All?

May cause redirected searches, failed keyword searches and/or the "File not found" error, Firefox can't find the file at jar:file:///C:/Program Files/Mozilla Firefox/chrome/en-US.jar!/locale/browser-region/region.properties

Disable or uninstall in Firefox via "Tools -> Add-ons -> Extensions". May need to uninstall via Windows Control Panel (see Uninstalling toolbars). May also need to reset preferences related to Ask.com (such as keyword.URL) viaabout:config.

AVG Safe Search

Installed with AVG 8 Free Anti-Virus (LinkScanner component).

8.0

Blocks use of ENTER key from the location bar.

Disable in Firefox "Tools -> Add-ons -> Extensions" or update to AVG 8.5

All?

Crashes, high CPU usage, cache is purged after restarting; Firefox remains in the processes list at exit causing "already running but is not responding" error when restarting Firefox.

Disable in Firefox "Tools -> Add-ons -> Extensions" or remove the extension by reinstalling AVG 8 without the LinkScanner component (see AVG faq# 1338).

Cooliris (formerly PicLens)

All?

Firefox may remain in the processes list at exit, causing a "Firefox is already running but is not responding" error (or problems with bookmarks, history, and toolbar buttons due to a locked Places database) when restarting Firefox.

Disable or uninstall the extension. Note:A conflict with the anti-phishing component of Norton 360 2.0 or Norton Internet Security 2008.5, if installed, can cause the hang at exit and locked Places database. As a workaround, disable Phishing Protection in Norton's settings or remove the Norton toolbar from Firefox as detailed here.

DownThemAll

1.0

May cause web browsing to slow to a halt to the point that nothing loads. 

Important: DownThemAll 1.0 changes certain "network.http" preferences that will need to be reset, even if you disable or uninstall the extension.

Update to version 1.0.1 and reset these preferences via about:config:

1. network.http.max-connections
2. network.http.max-connections-per-server
3. network.http.max-persistent-connections-per-proxy
4. network.http.max-persistent-connections-per-server

All (?) since 1.0

May cause Windows error opening Internet shortcut or local HTML file - Firefox

If updating DownThemAll to version 1.0.2 or later does not resolve the issue, disable or uninstall the extension.

external IP

Prior to 0.9.9.3

Causes Firefox crashes and authentication popups asking username/password for "Development Area" at http://www.crazzy.se

Update to version 0.9.9.3 or above

Fast Dial

2.16

Adds "spam" links to the Bookmarks menu, adds the UserLogos search plugin and makes it the default search engine, searches may redirect.

Update to version 2.18 or above (available from the Fast Dial Homepage). If necessary, delete unwanted bookmarks and change to your preferred search engine in the FirefoxSearch Bar.

2.15

Conflicts with the IE Tab extension (broken/blank Location Bar) and the Tab Mix Plus extension (oversized tab bar) , adds "spam" links to the Bookmarks menu, adds the UserLogos search plugin and makes it the default search engine, searches may redirect. May interfere with toolbars from other extensions.

Update to version 2.18 or above (available from the Fast Dial Homepage). If necessary, delete unwanted bookmarks, reset toolbar customizations and change to your preferred search engine in the FirefoxSearch Bar.

Fasterfox

1.0.x

Hangs or slows down Firefox

Disable prefetching, select "Optimized" preset instead of "Turbo".

All

Changes made by Fasterfox can interfere with Web site access and persist after it is uninstalled.

Reset options to defaults in Fasterfox before uninstalling it; otherwise, reset preferences in Firefox to the defaults (or create a new profile).

Filterset.G Updater

Prior to 0.3.0.2

Memory leak when used in conjunction with FlashGot

Update to version 0.3.0.2.

Firebug

All?

May cause excessive CPU usage; Firefox may hangwhen a pop-up window is accessed.

Disable Firebug when you don't need to use it

Prior to 1.3.2

Firefox crashes on logout from Yahoo! Mail, reported in Firefox 2. Note: Firebug 1.3.2 (and above) requires Firefox 3.

Disable Firebug when you don't need to use it.

Firefox Google Bookmarks

Prior to 0.2.1?

Interferes with spell checking in Firefox version 2.

Update to version 0.2.1. If that does not work, uninstall extension.

FireFTP

All?

Can cause excessive CPU usage with Firefox 2.0.0.1

Update Firefox to the latest version

FlashBlock

All

NoScript blocks JavaScript, which is required by FlashBlock

Do not use both FlashBlock and NoScript together (NoScript includes Flash-blocking functionality)

FlashGot

Prior to 0.5.9.995

Memory leak when used in conjunction with Filterset.G Updater

Update to FlashGot version 0.5.9.995 or later

ForecastFox

version 0.9.x and all satellite images versions?

Memory leak

Update or uninstall and installForecastfox l10n. There are unconfirmed reports that there are also memory problems with versions 0.9.3 and 0.9.4.

Prior to 0.9.5.1

Causes excessive CPU usage with Firefox 2.0 and Firefox 2.0.0.1

Update to Firefox 2.0.0.2 and ForecastFox 0.9.5.1

Free Download Manager 

(Firefox extension)

Prior to 1.3.4

The Free Download Manager application (FDM) installs an extension for Firefox integration which can cause Firefox crashes when right-clicking a Web page.

Download and install the latest version (FDM 2.5 build 758 will update the extension to v 1.3.4) . Note: The FDM extension (v 1.0 - 1.3.1) is on the Add-ons Blocklist; v 1.3.2 is not blocklisted but it also crashes Firefox.

Google Browser Sync

All?

Causes excessive CPU usage in general or with GIF animations

Uninstall

 ?

May cause notably increased disk usage (in gigabytes) by creating large log files. May cause periodic Firefox freezes.

Uninstall

Google Toolbar

Also available from the"official" Google Toolbar home page

Google toolbars are also bundled with other software

 ?

"Send with GMail" option overrides default mail client. If the Google Toolbar is uninstalled, mail links may stop working in Firefox

If still installed, UNcheck "Send with GMail" in Google Toolbar Options. If uninstalled, use about:config to reset the preference network.protocol-handler.external.mailto to true(double-click will toggle).

3.x (beta?)

Windows error opening Internet shortcut or local HTML file - Firefox

Disable or uninstall

3.1

New tab page option creates a thumbnail for each visit greatly increases size of places.sqlite

Right click the Google logo in the Google toolbar > Options > Uncheck “Enable the Google new tab page”

Greasemonkey

All

Greasemonkey scripts do not work on sites blocked by NoScript

Set NoScript to allow JavaScript on sites you wish to use Greasemonkey scripts on.

Hebrew Calendar

Prior to 1.0.4.36

Causes "ReferenceError: JEvent is not defined"

Update to a newer version

IE Tab

All

Memory leak

Uninstall IE Tab and install IE View Lite

iMacros

Prior to 0.5.0.4

Causes excessive CPU usage

Update to a newer version

ImgLikeOpera

0.6.15

"Refresh images in tab on tab select" option causesexcessive CPU usage on tab change and erratic text box behavior (i.e. losing caret after selection in google search text box).

Turn off "Refresh images in tab on tab select" option.

Linky

2.6

Gray bar below the status bar with red arrow.

Uninstall Linky.

LiveHTTPHeaders

All?

Uploading a file locks the file so it cannot be renamed, moved, or deleted.

Uninstall LiveHTTPHeaders.

McAfee SiteAdvisor

 ?

"onLookupFailed 55 1" alerts.

Disable McAfee SiteAdvisor.

22

Firefox may fail to open after installing or updating the SiteAdvisor extension, which also may be installed as part of a McAfee software suite.This SiteAdvisor support article describes the problem as a conflict between SiteAdvisor and automatic proxy configuration scripts in Firefox.

Either follow the workaround in the SiteAdvisor support article or end the firefox process that remains in memory, start Firefox in Safe Mode and uninstall via Tools -> Extensions. If SiteAdvisor is a McAfee suite component it can also be removed using the McAfee uninstaller.

23

Causes Firefox to crash with an error in Jar50.dll after installing or updating the SiteAdvisor extension or McAfee component.

Uninstall the SiteAdvisor extension or, if SiteAdvisor is installed as part of a McAfee software suite, remove the SiteAdvisor component using the McAfee uninstaller.

Media Player Connectivity

All?

Can cause Unresponsive Script Warning

Uninstall Media Player Connectivity

MegaUpload Toolbar

All?

Causes the error message, Trying to load a non-local URI. Also changes the user agent by adding "MEGAUPLOAD 1.0" which causes some websites to tell you to update to a modern browser.

Uninstall the toolbar. To restore the user agent, type about:config in the Location Bar and filter forgeneral.useragent. If thegeneral.useragent.extra.firefoxpreference shows a user set status, right-click it and select Reset.

Menu Editor

1.2.4 

(and 1.2.5?)

Middle mouse button no longer opens new links from web pages

Update to the latest version; if the issue persists, disable the extension

Mouseless Browsing

All?

Can cause excessive CPU usage

Uninstall Mouseless Browsing

Nightly Tester Tools

All

Allows incompatible extensions and themes to run; these incompatible add-ons can cause problems

Update your extensions and themes to those compatible with your version of Firefox

NoScript

All

Causes an illegal operation in the Windows Media Player plugin if it is blocking JavaScript on a page with embedded Windows Media

Do not block websites that have embedded Windows Media if you want to be able to play the media

FlashBlock requires JavaScript to work to block flash ads

Do not use both FlashBlock and NoScript together (NoScript includes Flash-blocking functionality)

Greasemonkey scripts require JavaScript

Set NoScript to allow JavaScript on sites you wish to use Greasemonkey scripts on.

All since 1.1.9.5

Flash and other plugin content is blocked by default on untrusted sites, even content from trusted sites (e.g. YouTube.com) if embedded on an untrusted site.

Uncheck the option to forbid Flash or other plugins in NoScript's Options\Plugins pane or temporarily allow the content by clicking on its placeholder.

All since 1.1.0

Java is blocked by default on untrusted sites

Uncheck "Forbid Java" in NoScript's Options\Plugins pane (Options\Advanced\Untrusted in earlier versions). In version 1.1.3 and later you can temporarily allow Java content by clicking on its placeholder.

Prior to 1.8.1.3

Cannot log into eBay or other sites with NoScript "Automatic Secure Cookie Management" enabled.

Update NoScript to the latest version.

"Numbered Links"

All

FormSpy (aka FireSpy) malware identifies itself as "Numbered Links". The real Numbered Linksextension is harmless. See this forum topic for more information.

Uninstall the extension. Scan your system for viruses, particularly "FormSpy" and "Downloader-AXM".

onFocusReload

 ?

"Alert! Object Event" message.

Uninstall onFocusReload.

PicLens

See above entry for Cooliris (formerly PicLens)

ProCon

Prior to 1.5.2

Replaces all words on webpages with asterisks (******) if set to "censure" words. Fixed in version 1.5.2.

Uninstall ProCon, restart Firefox, reset ProCon preferences in about:config, restart Firefox, reinstall.

RealPlayerBrowser Record Plugin 

This extension is installed as an option whenRealPlayer is installed.

1.0

May cause various issues including problems with form submission, embedded Flash, or images not loading after a refresh or revisit to the page.

Try updating RealPlayer, which will update the extension, or disable in Firefox via "Tools -> Add-ons -> Extensions". Note: the Uninstall button is "grayed-out", as this extension is installed via the Windows Registry. To remove from Firefox, open RealPlayer, go to Tools -> Preferences -> Download & Recording and uncheck "Enable Web Download & Recording".

?

May cause the Firefox 3 "Bookmark this Page" dialog to appear when clicking the Bookmarks menu item.

Updating to Firefox 3.0.11 or above should resolve the issue. If the problem persists, disable the extension or remove it in RealPlayer preferences (see above)

SearchStatus

All?

Causes Firefox to hang for short periods.

Uninstall SearchStatus

Skype Extension for Firefox 

This extension is installed as anoption when Skype is installed.

All?

Firefox may start with error messages and may run slowly. Google maps or other images may not load. Direct links to images or PDF files may cause the error, The image cannot be displayed because it contains errors. Web pages may continually refresh or stop loading. Firefox may stop responding orhang at exit, resulting in an "already running but is not responding" error (or problems with bookmarks, history, and toolbar buttons due to alocked Places database) when you next restart Firefox.

Disable or uninstall the Skype extension in Firefox via "Tools -> Add-ons -> Extensions" (the extension is not needed to use the Skype application). 

Note: If Norton 360 2.0 or Norton Internet Security 2008.5 is installed, a conflict with Norton's anti-phishing component can cause the hang at exit and locked Places database. As a workaround, either disable Phishing Protection in Norton or remove the Norton toolbar from Firefox (details here).

SwitchProxy Tool

All

Causes new Firefox windows to freeze for a few seconds

Disable SwitchProxy's auto-update feature

Tabbrowser Extensions (TBE)

All

General slowdown, conflicts with other extensions, can cause Firefox to not work at all

Uninstall TBE, use Tab Mix or Tab Mix Plus instead

Tabbrowser Preferences (TBP)

All (for Firefox in some languages)

Gray bar below the status bar at the bottom of the screen which reads:

<button id="catTabbedButton" label="&tabprefs.label;"

Uninstall TBP

1.2.8.4

Bar at the bottom of the screen which reads:

%tabprefsDTD;

Uninstall TBP and install it directly from the author's website

ThinkVantage Password Manager Extension

2.0

May cause Firefox to freeze for up to a few seconds when a new window is opened.

Disable or uninstall the ThinkVantage Password Manager extension in Firefox via Tools -> Add-ons -> Extensions. (Note: The Uninstall option may be greyed out, if the extension was installed via a Windows Registry entry).

2.0

May cause a "Failure in chrome registration" error when starting Firefox. 

Note: In Windows Vista, exiting Firefox, right clicking the Firefox icon and selecting "Run as administrator" may resolve the issue; if not, use the workaround.

Disable or uninstall the extension (from Firefox Safe Mode if necessary) if you don't need it. Alternately, find the filetvtpwm_moz_xpi.xpi (usually in "C:\Program Files\Lenovo\Client Security Solution") and open it in Firefox to reinstall the extension.

2.0

Firefox crashes when opening a pop-up window. Caused by the latest Lenovo Client Security update.

Disable the extension or reinstall it by opening the file tvtpwm_moz_xpi.xpi in Firefox (see above)

Torbutton

 ?

Interferes with cookie deletion.

Check Torbutton options or uninstall Torbutton. Then recheck Firefox options. It may be necessary to "delete cookies-nontor.xml".

 ?

Changes privacy and security settings.

Check Torbutton options or uninstall Torbutton. Then recheck Firefox options. Repair or replace the Firefox profile if necessary.

 ?

May cause Firefox performance problems.

Check Torbutton options or uninstall Torbutton. Then recheck Firefox options. Repair or replace the Firefox profile if necessary.

Update Notifier

 ?

A prompt for a username and password fromhttp://mozdev.elliptic.fr/ asking "Oui?"

Uninstall Update Notifier

User Agent Switcher

Prior to 0.6.4

Reinstallation or update causes Firefox to hang

Uninstall previous version in Safe Modebefore installing new version

VeryDelicious

All

Software update screen on opening windows and downloading fiiles.

Uninstall VeryDelicious

Web Analytics Solution Profiler/Debugger (WASP)

Prior to 1.0.9

On Mac OS, installing this extension sets the~/Library/Caches/TemporaryItems folder to non-writable, causing Download Error -228 and inability to install add-ons.

Open the /Library/Caches/ folder for your Mac user account, context click (right-click) on the "TemporaryItems" folder, choose "Get Info" and, under "Sharing and Permissions", change permissions to "Read & Write".

Wizz RSS News Reader

2.0.0

Update causes Firefox to hang

Uninstall previous version in Safe Modethen install the updated version.

Woot Watcher

1.0.1 (all?)

Periodic Firefox hangs, slowdowns, or excessive CPU usage, possibly related to Woot Off events.

Disable or uninstall the Woot Watcher extension

XPL LinkScanner

2.6

Causes Firefox to crash when using Yahoo, Google, or MSN Search. This extension may be installed in Firefox as part of "System Suite 8" by AvanQuest.

Disable or uninstall "XPL LinkScanner Firefox 2.6" via Tools -> Add-ons -> Extensions.

Yahoo! Toolbar

All?

Causes excessive CPU usage

Uninstall via "Tools -> Add-ons -> Extensions" or use these instructions.