I have Firefox 4.01. When Firefox is left open on my PC overnight when I go to use my PC in the morning I see that it has crashed. I uninstalled Flash with the uninstaller program then reinstalled it so I don't think it's that which is causing the problem. I submitted the crash report when Firefox asked me to.

I don't want to upgrade to a newer version of Firefox because my Multirow Bookmarks Toolbar extension doesn't work with newer versions of Firefox yet.