Thanks for the suggestions, guys!
Tried them all without a fix. The problem as per the blue screen of news you don't want to hear was that the video driver was in an infinite loop and Windoz shut down to prevent damage to the computer.
The puzzling part was the random occurence frequency---I could sometimes play for @ 3 hours without a hitch and sometimes only about 5 minutes---it once did it as soon as the loading screen appeared.
After playing for a couple of intense hours the other night, it crashed but on reboot, the graphics was like a bad acid trip---couldn't get beyond 640x480 res and 4 bit colour. AHA!
A new vid card (a story unto itself for an AGP motherboard) has it back to smooth operation, albeit lower settings due to a less capable card.
Just thought I'd let you know.