Why is Firefox randomly reopening itself after quitting?
I had the same problem ! I downloaded version 3.5 for mac &amp; it works fine for me now.

Please Take Note of following.
Even in FireFox version 3.5, I faced a strange behavior.
When I try to open a new tab sometimes it goes adding new tabs in bulk, I mean infinite loop of adding new tab. In that case, I used to quit fireFox by force. ( force-Quit ).
It happens quite frequently, even though I couldn't determine the exact steps to produce that bug. So, If you face same kind of behavior, please let me know by comments.