Does it make any difference what pages you have open when you Exit Firefox?

(By Exit I mean choose Exit from either the orange Firefox button menu or the classic File menu, instead of using the red X button to close the window.)

If there's no pattern with pages, it could be a compatibility issue with one of your extensions... or something else.

When Firefox crashes, it usually records information about what was happening at that moment. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the support article "Firefox Crashes" (especially the last section) for steps to get those crash IDs, and then post some of the recent ones here.

Since you asked I paid attention and as far as a can tell, running many tests, it happens on 2 banking sites. It happens if I use the "X" or "File>Exit" . I do not have any addons or extensions enabled (I disabled everything when this started happening. The error says "Firefox has stopped working - Windows is checking for a solution". Then, it opens a 2nd window "Firefox has stopped working - A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available" I only have the open the click on "close program". I "close program" and that's the end of the messages.

I've looked through all of Firefox solutions and tried suggestions. Do you have any idea if it might be something on the websites?

THANKS

Interesting results! Over the years some versions of Trusteer Rapport, which users install at the instruction of their banks, have created problems in Firefox. Otherwise, I can't think of anything specific to bank sites. Except the possibility of a malware infection. This article lists some tools you can use to supplement your regular security scans: Troubleshoot Firefox issues caused by malware.

Regarding the crash data, if Firefox's about:crashes page does not contain relevant data, you could try the Windows Event Viewer as described in this Microsoft support thread: "appcrash" events are showing in the event logs - Microsoft Community. I wasn't able to find any examples in my own event log.

Good news so far. I reinstalled Firefox and so far no problems. I have reinstalled more than once before so I'm not at all sure why this time is different!

I did get event log entries: Faulting application firefox.exe, version 26.0.0.5087, time stamp 0x52a0d273, faulting module xul.dll, version 26.0.0.5087, time stamp 0x52a0d20a, exception code 0xc0000005, fault offset 0x0014e1a8, process id 0x4228, application start time 0x01cf00582d9fd7f0.

I'm hopeful that the reinstall resolved it but It would be nice to know why?!?

THANKS for all your help

FYI, same problem occuring. Firefox crashing on exit!! I uninstalled it and will just move to a different browser. Thanks for your help though.