@xvader - Bingo! I was comming back to report that I had solved the problem. I too was puzzled and running out of ideas. I figured what the heck, since the last drivers were released over a year ago (the ATI HD3400 is considered "legacy" now). I reinstalled them and the problem magically went away. I guess some update mangled things somewhere and that put it all back where it needed to be.
Final verdict - Video Drivers...... Install them again, even if they're not an update and logic says it's not necessary - reinstall.