Are you saying bad things like a infection?
No--it just removed files or folders that it apparently shouldn't have. Even after that, Firefox kept "not responding" upon occasion (some files/folders could not be returned from the Recycle Bin!). I fixed that by removing and then reloading Firefox (which had just upgraded to 3.6 in the process).
I think that all is basically well at the moment, except that all defragger programs except one (Diskeeper 2010) claim that my D drive is hideously fragmented. Diskeeper claims it's fine.