Standard diagnostic - SeaMonkey
From MozillaZine Knowledge Base
This article offers a step-by-step guide that users can follow if SeaMonkey is no longer working properly and no other application is exhibiting strange behavior.
Standard diagnostic steps
Before troubleshooting, completely close your Mozilla application (or reboot the computer) and then restart it. If the problem persists, go through these standard diagnostic steps:
- Note: Many problems are caused by incompatible themes, extensions, or programming errors in plugins. As a quick diagnostic, you may wish to switch to the default theme or, if the problem appeared after installing a new extension or after upgrading SeaMonkey 2, use the Add-on Manager (accessible from the Tools menu) to update or disable your extensions, before going through the diagnostic steps below. Plugins can also be disabled using the Add-on Manager.
- (If you can open SeaMonkey and use the menus) clear the cache and remove any private data you don't wish to save, such as cookies or browsing history ("Edit -> Preferences -> Privacy & Security / Private Data -> Clear Now") . If the problem persists:
- Close SeaMonkey (if open) using "File -> Exit (or Quit)" and make sure it is not running in the background (on some systems, you may need to wait awhile for the SeaMonkey process to terminate). Optionally make a profile backup to safeguard your data and settings and then:
- Theme and extension issues (and hardware acceleration): Start SeaMonkey in Safe Mode. If the problem persists in Safe Mode, continue with the next numbered step. If the problem goes away in Safe Mode:
- (SeaMonkey 2.1 and above) Turn off hardware acceleration ("Edit -> Preferences -> Appearance / Content", uncheck "Use hardware acceleration when available").
- Update or uninstall the added theme or select the default theme in "Tools -> Add-on Manager -> Themes".
- Update or selectively disable or uninstall your added extensions in "Tools -> Add-on Manager -> Extensions".
- Plugin issues: Java, if installed, can be disabled from the Advanced panel of your SeaMonkey Preferences. You can view all installed plugins via "Tools -> Add-on Manager -> Plugins" and disable them individually, to see if a plugin is causing the issue. If the problem still persists:
- Profile issues: Create a new SeaMonkey profile (you can later use the Profile Manager to return to your original profile). If the problem goes away in the new profile, you can selectively copy your important profile data to the new profile. If the problem persists, continue on with the next numbered step.
- (Optional) If a new profile resolves the problem you may be able to fix your original profile by manually removing certain files from the profile folder (the files will be regenerated on next startup). Back up your profile (if you have not done so previously) then, with the application completely closed, delete (or rename) the files places.sqlite (and "places.sqlite-journal, if found), downloads.rdf localstore.rdf , mimeTypes.rdf, "extensions.ini", "extensions.cache" and "extensions.rdf". Also find and delete the Cache folder and the file "XUL.mfl" (Windows), "xul.mfasl" (Linux), or "XUL FastLoad File" (Mac OS X), which may be located outside the profile folder (see Profile folder - SeaMonkey for details).
- Clean reinstall: Download a new SeaMonkey 2 installer and then close SeaMonkey completely, delete the SeaMonkey program files and reinstall SeaMonkey 2. If this does not help, you may need to uninstall SeaMonkey completely before reinstalling it. 
If the issue is still unresolved, see the other solutions listed below.
Applies to Mozilla Suite/SeaMonkey 1.x (now obsolete)
- If you can open the program and use the menus, clear the cache ("Edit -> Preferences -> Advanced -> Cache -> Clear Cache") and clear any other private data you don't wish to save such as cookies and download history. If the problem is not resolved:
- Theme issues: Switch to the Classic or Modern theme ("Edit -> Preferences -> Appearance -> Themes") then restart your Mozilla application. If the problem persists, continue on.
- Close the program (if open) using "File -> Exit (or Quit)" and make sure it is not running in the background. Do not skip this step.
- Extension issues: If you have installed any extensions and can open the program and use the menus, uninstall your most recently installed or updated extension (or uninstall all extensions), then perform step 3 again and start your Mozilla application normally. If the problem persists, continue on.
- Profile issues: Perform step 3 again, back up your profile (as a precaution) and then create a new profile. (You can later use the Profile Manager to return to your original profile.) If the problem is resolved, selectively copy back your important profile data to the new profile. If the problem persists, continue on with the next numbered step.
- (Optional) If a new profile resolves the issue, you may be able to fix the original profile by manually removing certain files from your profile folder (The files will be regenerated on next startup). With your Mozilla application completely closed (perform step 3), delete or rename the files downloads.rdf, history.dat, localstore.rdf, mimeTypes.rdf, and the "chrome" folder contents. Also find and delete the Cache folder and the file "XUL.mfl" (Windows), "xul.mfasl" (Linux), or "XUL FastLoad File" (Mac OS X), which may be located outside the profile folder (see Profile folder - SeaMonkey for details).
- Windows only: Plugin issues: Close the program completely and remove the contents of the installation directory plugins folder (e.g., C:\Program Files\mozilla.org\SeaMonkey\plugins), to a backup location. Note that this will not disable plugins found via plugin scanning. If the problem goes away, it was caused by one of the removed or disabled plugins. If the problem continues, see Issues related to plugins for additional plugin diagnostics. If the problem persists:
- Do a clean reinstall:
- Uninstall Mozilla Suite/SeaMonkey.
- Delete the installation directory. Note: If Mozilla Suite or SeaMonkey 1.0.x is installed on Windows, also delete the GRE directory for the application version, located here: C:\Program Files\Common Files\mozilla.org\GRE.
- Open your OS temporary directory (Windows 98/ME: Start -> Run -> Type
C:\Windows\Temp -> OK, Windows 2000/XP: Start -> Run -> Type
%temp% -> OK) and delete all files and folders contained therein.
- Download the SeaMonkey installer from the SeaMonkey Project page and re-install (Mozilla Suite is no longer supported).
If the issue is still unresolved, see the other solutions listed below.
- Check your firewall or other security software settings to ensure that your Mozilla application or specific web content is not being blocked.
- An ad-blocker, web-accelerator, antivirus or other running program may be causing a conflict. Try temporarily disabling these other programs one at a time.
- (Windows) Run the error-checking tool Chkdsk (Windows 2000, XP) or ScanDisk (Windows 98, ME).
Check for malware
Scan your system for viruses, spyware and other malicious software. Your installed security software may not detect the malware so you should also install and run these specialized malware removal programs:  
You can post in one of these forums for malware removal help: