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Firefox will not close properly at the end of a session.


Clicking the "X" close button or selecting "close window" from the system tray icon causes the window to close, but when I try to start a new session I get a window saying "Firefox is already running but not responding." I have to use the Task Manager to "end process" the program before I can start a new session. I reported this last week as an intermittent problem, but it has become constant, as in every time. This happened occasionally (once a month or so) in prior releases, but since the 5.0 release it has quickly gotten significantly worse, until now the only way I can close the program successfully is through the task manager.

Additional System Details

This happened

Every time Firefox opened

This started when...

Almost immediately after the 5.0 release

Installed Plug-ins

  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Adobe PDF Plug-In For Firefox and Netscape 10.1.0
  • Shockwave Flash 10.3 r181
  • Adobe Shockwave for Director Netscape plug-in, version 11.5
  • Next Generation Java Plug-in 1.6.0_26 for Mozilla browsers
  • 4.0.60531.0
  • Zeon PDF Plugin For Mozilla


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0) Gecko/20100101 Firefox/5.0

More Information

Unable to find any reference in the help files.

  • Top 10 Contributor
  • Moderator
10783 solutions 97065 answers

See "Hang at exit":