Looking for some help.

Thanks again, Paul! That's a good list of experiments to try to track
down the problem. I have put this machine aside for now, and will
start
the investigation in earnest this weekend. Thank goodness I have an
iMac to use in the meantime. I put a lot of $ into this PC for the
last
couple of years, thought I was buying high quality stuff--but
somewhere
along the line, there was a weak link. Cheers!