OK, this is copy/paste from my reply to Mike:
Win XP? Here is wonderful article on Microsoft web site:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q318378
100% helps... I've been there, done that...
Regards !
not sure if this will help
months ago my system folder became scrued up.
I reinstalled win-me. but had to deal with "migration" troubles.
eventually I had ie5.5. then managed to update it to ie6.
BUT, winupdate still kept trying to perform the ie setup for ie6. I tried
all of the download, install procedures offered by winupdate.
still it kept telling me I needed some ie6 components. (I can't recall
exactly)
then I realized I could Win Restore to a time before the system folder mess.
I did that and that fixed the problems. after the restore, I only had to
reinstall a few minor apps. I reinstalled only apps that wouldn't run after
the win Restore..
I hope I'm recalling this correctly.