I had major problems with my 8790. I think I re-installed WinXP like 7 times in two days. (back in September).
I couldn't find what the problem was. Still to this day I'm unsure, but I'm still betting it's MobiMeter.
After installing Service Pack 2 and then installing MobiMeter the computer just used to hang at random. And totally screw up my installation.
So after doing one more fresh install of WinXP with SP1a, I didn't install MobiMeter. Ran it for a few days installed other apps. No freezes.
Then I install Service Pack 2 and still NOT installing MobiMeter. Everything was still fine. And still running fine to this day.
Best bet is that MobiMeter doesn't like SP2.