Thanks for the quick suggestions!
I went into the xp safe mode with networking ok via msconfig.
I went to downloads and tried to get the tweaking.com install files that i downloaded yesterday to run, but nothing happened, as before. Clicked on 7-zip install file that I downloaded before and it starts up with no problems, as before. Also tried to download and install ccleaner from yesterdays file, but it does not run, as before
Tried to run portable tweaking program from flash drive and it started up and got to "installing windows files" at around 75% before the BSOD.
Note that the only internet connection I have on the problem pc is a pci wifi card. No ethernet connection nearby. Luckily the wifi card works. I am sending this message from the problem pc wifi.
Next?
Dave