I'm running XP, and after a windows update I was getting svchoste.exe errors. This cause a range of weird errors on my machine, like the theme going back to XP Classic and a selected number of things not working.
I was ready to spend the morning rebuilding my lappy...when i found this hotfix (KB894391). I ran it, rebooted and my machine is happy again 
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Why aren't I running Vista you all may ask...cause Dell lied about the Vista upgrade eligibility.