FIREFOX

If you've upgraded to Firefox 1.5 (and you should have!), go to Tools->Extensions and look for updates to your extensions. A lot of them have release 1.5 compatibility patches. After you've upgraded all the ones that could be upgraded, remove the ones that are still marked in Red. I had a couple still installed and even though they were disabled one of them was causing weird HTML problems. As soon as I uninstalled them, all the issues went away.

Also, if you use the Javascript console I recommend installing Console². The new Console includes CSS errors and if you visit many pages your console will very quickly fill up with stuff you don't care about. Console² allows filtering of the Error Console so it's usable again.

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