OK, underlying problem fixed. And, for those who jumped at conclusions, it's not a MA3 problem with Windows 7.
[There was this guy who jumped at the conclusion of a mule ... but I digress]
Same hardware (computer, video card, etc.) - just upgraded from XP to W7? Same monitor? Same two cables connected on both ends?
Yes to all questions, except you can't upgrade xp to win 7 so it was a new install on a new hard drive.