Sometimes simply removing the profile folder itself will do the trick, too. Start Firefox with the Run prompt using "firefox.exe -P" and create a new profile, then go to "%APPDATA%MozillaFirefoxProfilesxxxxxxxx.default" in Explorer and delete the default profile. I’ve had to do that before, back when Firefox 3 came out I think.
Back on topic, though, I hadn’t noticed that, ikthius. I’m upgrading Safari 4 as I speak, though.