This has been happening to me for many months, and apparently to many other people as well. After a variable amount (minutes, hours, days) of multi-tab browsing, Firefox fails in one or more of the following ways: * new CSS stops loading (cached ones still work) * new images stop loading (cached ones still work) * JavaScript stops working * new URLs stop working (cached pages still work via back/forward) * Error Console, Preferences, etc stop working The one symptom that remains true across all manifestations is that normal Quit (whether from the menu bar, dock, or cmd-Q) does not work, and Force Quit is required (sometimes twice). After reopening Firefox everything works again... until next time. Since the bug never leaves a crash log behind, and there is no clear defining trigger, and the symptoms are so variable, I do not know if the other reported bugs here are duplicates or independent.

in addition to your initial blockers: bug 379795, bug 383700, bug 390264, bug 402296, bug 402371, bug 424271, bug 424337, bug 430941, bug 475161 there are 412382 Firefox hangs when quitting browser or applying update 410897 Firefox 3.0b2 crash on quit 449980 Firefox hangs when you try to quit the browser and have "Ask every time" set as default 474980 Hang on shutdown after being open for a while 479373 Hang on shutdown if there are outstanding SSL requests 474699 Sometimes the shutdown of Firefox takes ages while consuming 100% cpu load But, if this didn't start for you until FF3, does it make sense to cite bugs here that began in FF2?

I have not seen this happen any more in FF3.5.

No problems either here with FF 3.5.3 under Mac OS X 10.4.11.

The bug seemed to appear with FF 3.5.4, but only one URL was affected: one of the images from mailgraph.cgi (the other images were not affected). Firefox was trying to open the URL, but nothing happened (not even a timeout). Stop + Reload didn't have any effect, and "Live HTTP headers" didn't show any HTTP request (and the web server didn't receive any request). No problem with "wget". So, I eventually restarted Firefox and the problem disappeared.

Vincent, can you please file that as a new bug? This one is a tracking bug. Please CC me because today I already had another user who complained about that. Thanks.

I see a lot of bugs out there, both NEW and UNCONFIRMED, about not being able to quit gracefully on Mac. I'm seeing this behavior for the first time running FF 3.6 on Snow Leopard. I'm having difficulty reproducing, but it happens just about every time I leave FF running for a long time. Since I have to force quit, and it doesn't seem to be a crash, will a stack trace be generated (or be helpful)?

See also Bug 1008609. I've been able to reproduce on very short sessions, and it seems to be related to clearing cached content. In the old days, it just rm'd the whole sub-directory structure -- a couple of years ago that was changed to a loop. It's now spending a lot of time in that loop, even though the panel says 0 bytes cached.

Only one open item left (bug 430941). Tracker is no longer needed.