Hello Raymond,
I would hate to give up so quick. On the other hand you tried all the typical things I could think of and would have tried too.
What you discribed sounds to me 99% like a memory issue, but you said it isn't. If it is not a corrupt installation of the framework I could imagine some other things like virus or XP installation issue (no, I'm not suggestion to re-install WinXP just for CPT :).
The thing is that it hardly can be a problem of CPT itself if it worked already fine.
Did you try to use the training center with a new and very small repertoire?
Regards,
Stefan