@magicalclick: A friend of mine managed to get Firefox so completely hosed on her Mac that even reinstalling it couldn't bring it back to life. She was forced to switch back to Safari. Just being able to reinstall it doesn't guarantee you can fix the problem that way.
Not to mention the fact that no version of Windows ships with IE9. Which means you should've been able to remove and reinstall it.
And you didn't answer my question about running without add-ons. Did you try that, and if so what was the result?