I just want one that works. I don't care which one it is. Except maybe Google's. If I use Revo to uninstall FF 3.6.16, it updated itself, run CCleaner then do a clean install of FF4 do you think it'll work? I don't want to have to mess around with three or four different browsers.
You could do all that, and it might work, but I'd guess you're better off following FF4's troubleshooting guide.
Start from the main help page (Menu Help->Firefox Help), follow the Basic Troubleshooting guide - it's not too long and covers many problem sources.
BTW, the ideas there apply to other browsers as well, you just don't get nice step by step instructions for those.