Hmm, seems as if I may have won that small amount of money.
Sure -- try installing an update to your video driver, if one is available. If not, you can try working in a different resolution full-time and see if that helps. Finally, you could always switch to a different video card entirely.
Since this doesn't really seem to have anything to do with VNC per se, I don't know that any VNCViewer changes or bugs apply. (Still, you could experiment with the mirror driver, alpha blending on the server, etc.)
If it were me and nothing else worked, I might write a small batch file to automatically switch video modes on demand. There are lots of system tray tools that will do that too.