Letsparty24/7
A short while ago, I tried the suggestion by
low'n'fast and, it seems to have worked..!!
I had previously uninstalled Adobe Reader 7 as it was causing problems.
So, I ticked the box as suggested, shut down pc totally (rather than restart), gave it a few minutes to calm down, and then restarted it.
I then installed Adobe Reader 7 (again) and it now seems to open some of the pdf files on the pc.
I've only tried opening a couple of pdf's, one of which was 160 pages long, which opened fine, and it also closed ok. And the pc continues as normal without cpu showing 100% useage.
Definitely worth a go.
Cheers
low'n'fast 
HJ