I just ran a registry clean, as I have done at least a dozen times before, but this time somehow both Firefox and IE browsers are now completely broken - no page renders correctly, menus don't show up, no text is shown, etc (for example, here's google's home page: http://i.imgur.com/KOgvzcX.png). They are both completely unusable. Naturally I didn't make a registry backup this time, since I've done these exact same steps at least a dozen times without issue. I was able to install Chrome, which has never been on this computer, and it seems to work fine, but both browsers that were installed at the time of the registry clean are broken. I've tried uninstalling and reinstalling, creating a new Firefox profile (difficult when you can't see any menu text), starting in safe mode, re-running ccleaner to see what happens, and nothing works.
Does anyone know what the devil happened? Barring that, is there a proper way of nuking Firefox completely and starting from scratch? (Since Chrome works after never having been installed, I'm working under the theory that if I can get a truly clean install, FF may live again)