Thanks for the input everyone...problem solved!

After running the SFC tool, it showed nothing out of the ordinary. I had used system restore to a point before the games were loaded, w/o solving the problem.

Since I couldn't get any app to load, I thought I'd check to see if I could at least start an XP reinstall. That terminated itself, too, so it was a good diagnostic tool as far as I was concerned. Leading me to suspect some change to the system prior to the game install/uninstall.

Turns out it was a corrupted "Windows Update" download of the "compatibility wizard update." I don't know if the problem is inherent to the coding of the update itself, or just a glitch encountered during the download process. [I've got to believe it was the data transfer...]

After restoring to a point before that, everything is back to normal. I've re-installed all critical updates but the suspected wizard update, and all is well.

Thanks again for the brainstorming help!