Mucman,
RAM may be the problem. One time, I was buildinga computer, and every time that I would install windows, explorer kept crashing after a few minutes. GPF's and errors every all the time. I kept on reinstalling thinking I was doing something wrong. Checked all the components, and everything was seated fine..even replaced the hard drive. Same thing.
Finally, I replaced the memory, and everything worked properly. What had happened was when you install windows, during installation, it sticks as many of the files into RAM. Basically, it puts explorer.exe, the kernel, and some other files into memory, so it doesn't access the CD. if you have bad memory, and windows stuck these finals into memory during installation, it gets messed up. Check the RAM
that's my $0.02. good luck