I have encountered this problem off and on. Below a list of possible reasons for Firefox hangs:
Potential Sources for Firefox Hanging
- User Agent Switcher
- MS Anti-Spyware
- McAfee Antivirus
- Adobe TypeManager/ Font
- Changes regularly as extensions are updated – post the extension you are having problems with below.
The reasons for this problem vary but here are some troubleshooting tips to try when Firefox stalls or hangs to get you back up and running. My solution for the moment is to clear the cache, and reduce the memory load. I also had a problem with the Tabbrowser Extension (known also to conflict with FCKEditor and TinyMCE, among other things), which I replaced with TabMix Plus, and that seemed to solve the problem. Another extension that I think is great but unfortunately is experiencing extreme memory leaks is TagAlert. Hopefully a future release will solve the memory leak issues.
If All Else Fails
If all else fails reinstalling Firefox, disabling all extensions, and doing the following will almost always solve any issue:
Windows: Rename the “Firefox” folder in the following directory: C:\Documents and Settings\USERNAME\Application Data\Mozilla to something like “Firefox-bak” and reload Firefox. Post any questions below.