I'm not exactly sure what caused the problem, but when I opened up Firefox this morning, I was unable to use the menu or the icons; I appeared to only be able to right click the menu bar and left click the updated extensions icon. I had thought that one of the extensions I had upgraded the previous night was the problem, but deleting them manually did not fix the problem. I ended up having to delete my Firefox profile (backing up my bookmarks) and that fixed everything. I've reloaded the extensions I was using and things are still working. I'm wondering if the profile just became corrupt somehow, or if the theme I was using got updated even though it shouldn't have, as the updated extensions icon was showing up in a different place (I'm still on 1.0.7, as Gentoo Linux has not made 1.5 stable yet) and the latest version of the theme only supports 1.5 and up.
Has anyone else experienced this?