Closing the Firefox process using the Task Manager is handled by Firefox just like a crash would be handled. That is why you are getting the "Restore Last Session" page. You need to determine the reason for what is referred to as "hanging at exit".

Sounds like it is hanging when you exit and later try to restart Firefox.

• How to stop the running Firefox process
  • In Task Manager, does firefox.exe show in the Processes tab?
  • See: http://kb.mozillazine.org/Kill_application
• What may cause Firefox to hang at exit
  • http://support.mozilla.com/en-US/kb/Firefox+hangs
  • http://kb.mozillazine.org/Firefox_hangs
  • https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding
• You may need to try Firefox Safe Mode
  • You may need to use Safe Mode to locate the problem: http://support.mozilla.com/en-US/kb/Safe+Mode
  • Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox. If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes before starting Safe Mode. When entering Safe Mode, do not check any items on the entry window, just click "Continue in Safe Mode". Test to see if the problem you are experiencing is corrected.
  • If the problem does not occur in Safe-mode then disable all of your Extensions and Plug-ins and then try to find which is causing it by enabling one at a time until the problem reappears. You MUST close and restart Firefox after EACH change via File > Restart Firefox (on Mac: Firefox > Quit). You can use "Disable all add-ons" on the Safe mode start window.
  • See the following for more information
    • http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes
    • http://support.mozilla.com/en-US/kb/Troubleshooting+plugins
    • http://support.mozilla.com/en-US/kb/Basic+Troubleshooting

In addition to your question, I noticed that you have an out-of-date plugin (click "More system details..." next to your original question posting for a list of the plugins reported with your post). The plugin below has known security issues and should be updated.

• Next Generation Java Plug-in 1.6.0_21 for Mozilla browsers

1. Check your plugin versions: http://www.mozilla.com/en-US/plugincheck/
   • Note: plugin check page does not have information on all plugin versions
2. Update Java:
   • Download and update instructions: https://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox
   • Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml
   • Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions
   • After the installation, start Firefox and check your version again.

Fiddlesticks. Fact is Firefox does this every time you select Save and Quit. It's been this way long enough for a fix to have been developed. It's a real nuisance, and it's very unfriendly to newbies because they do not usually muck about in the Task Manager. Your esoteric technical fixes don't make it. IE doesn't exhibit this behavior. No reason for Firefox to do it. Just a darn nuisance.

jec3:

The information provided works well for most users experiencing the "hang at exit" problem; at least those users who respond and let us know that the problem was resolved by using the information provided.

Your comments indicates that your problem occurs "every time you select Save and Quit" which I have not seen posted here in conjunction with "hanging at exit".

Please post a new question with full details of your system configuration, your Firefox configuration and a detailed explanation of the problem and when it occurs; someone may be able to help you.

Remember: We are all uncompensated volunteers here; users helping other users experiencing Firefox problems. There are no Mozilla Firefox employees here. When posting in this forum:

• always be courteous and save your rants for some other arena
• ask or comment courteously and you will be treated likewise.
• if your problem is different from the one in the Original Post, look for another post that more closely matches your problem to look for an answer
• if you can not find a post that closely matches the problem that you are experiencing, the post a new question with as much detail as possible about the problem, your system configuration and your Firefox configuration.

The problem is the Java Plug-in. And updating to the current plug-in does not solve it. I sent numerous crash reports (still do) to Mozilla and heard nothing.The problem is made even worse when you throw AD-Block Plus in the mix. I finally uninstalled that after going to their website and seeing other people had the same issue with it and Java and Firefox. The problem stops images and certain websites from loading through Firefox...including the NOAA website...which Firefox takes two refreshes or back button trys on to find the server. Firefox and Java need to deal with issue and get it solved and quit the beta progression until they do.

I have the same problem - every time I close firefox (using either the red x or by selecting file ---> exit) the program appears to close normally, but the firefox.exe *32 process continues to run. If I try to re-open firefox normally I get a message that the program is still running and I need to go into task manager and manually kill the process.

I could also kill the process from the command prompt, but both of those methods are slow and annoying. This issue has only been occurring for the last 24 hours or so; to the best of my knowledge I haven't downloaded any new software or updated any plug-ins that would have caused a switch from firefox's normal awesomeness. Norton doesn't show any new viruses or other nastiness on my computer.

I'm running 64 bit Windows 7 Home Premium edition.

Fiddlestyx is right, mine has been like this for years and now here it is again in firefox 4? That officially makes the programming team incompetent as the guys that write winblows code. Your a joke. Everytime I get this error, I open Chromium!!!!!!!!

FattyZ

Although fattyz's comments are a bit strong, I am amazed this problem exists for so long. For me it is over a year. I get tired of going to a site that insists on opening new windows (which don't open and Firefox hangs on exit). Can't even open a new window from the "File" tab without this happening. JAVA is the only known add on I use - Nothing else knowingly installed by me. Is Flash an add-on?

I am strongly thinking of giving up Firefox and moving to IE8, but it has an autocomplete feature that is annoyingly intermittent and uncontrollable.