I did not have this problem until I updated to 4.1 the older versions worked fine.
Are you really running Firefox 3.0.8? For security reasons, you should at least update to 3.6.17 if not 4.0.1.
Firefox does require some time to shut down and perform housekeeping on settings files in your profile. But assuming you have a reasonably fast system, I would think 15-30 seconds would do it.
In Windows XP, Firefox windows sometimes would vanish from the Task Bar for no apparent reason, but I could switch to them by hold the Alt key and pressing Tab to call up the window switcher. Haven't noticed this issue with Windows 7.
When you get this error, try opening the Windows Task Manager (Ctrl+Shift+Esc):
(1) Is Firefox on the Applications tab? In that case, try switching to it.
(2) Is Firefox.exe on the Processes tab? (Note: this tab usually is not in alphabetical order, but you can sort a column by its name.) If so, it may have "hung" trying to clean up and exit. The following troubleshooting article might help:
I up dated to version 4.1 and it did not stop fire fox from still running after i close it down, in some cases i have to restart my computer in order to get back online using Fire Fox if i can not resolve this soon i will have to resort Internet Explorer, Error message i keep getting states fire fox is already running and i must close that window before i can open a new window. Any help is Greatly Appreciated
The steps I posted involving the Task Manager, and the article I linked, are the best help I can give without actually laying hands on the system. Hopefully those can guide you toward a solution.
You can check the installed Firefox version via Firefox > Help > About Firefox
You may have a corrupted user agent that identifies you as Firefox/3.0.8
See also "Hang at exit":
I have had this problem w/FF hanging up after I exit thru at least the last two versions. I just downloaded 4 & it started out fine but now it's hanging up again.
I know how to go to Task Mgr & knock it down but I want it fixed. This is really a pain in the butt to have to keep ending it thru TM. I don't care for IE & love FF but some of the issues are starting to get to me.
I just had a huge issue w/one website & not being able to open most of the pages w/i that site thanks to a popup problem.........no matter what I did, it didn't work. I went to FF 4 & now it seems to be ok. I've used FF for yrs w/no issues at all & now there's way too many issues. I'll soon be looking for another browser.
Anyone know how to fix this once & for all so it won't hang up??????
I have solved my issue with fire fox running after i close it down, I uninstalled fire fox again, But this time, I cleaned my registry with reg first aid, Then I downloaded a fresh copy of fire fox 4.1 and installed it, And so far so good it has been working fine. I hope this helps any one who may have the same problem, Good Luck.