See if this Microsoft link helps. There are 5 pages, 20 on a page for Windows Updates problems.
Hi, I used system recovery to recover my computer in its original condition a couple months ago because there were some other problems going on with it, and just felt starting fresh was the best way to go. Since then Windows Update will do nothing, it shows no history, will not scan so I show no critcle updates, this is concerning. Also my HP Update software dosen't even open, when I click on HP Center I recieve window stating " C\WINDOWS\pi1.exe is not valid Win 32 application". At first I thought I deleted something adware or spybot found related to updating these products. After reinstall I was able to do 1 scan and download at WU but it took me hours to do this, turned out I needed to download, update software, I think, then nothing since. I've read and read nearly everyday anything I can for a fix but nothing. I run Windows XP SP1,
Internet Explorer v6.00 SP1. I've shut down popup blockers, all my anti virus tools are updated and pc is clean, runs great actually. Do you think I should reinstall XP, if so how to start? Any ideas would be appreciated. Thanks