Weird multimonitor problem

I have been using multiple monitors for several years and have had few problems. I recently purchased a new computer with a Radeon 800XT PE video card and it has been awesome. I have two monitors on it, one through the VGA and the other through the DVI. It has worked fine until recently. Suddenly I find when I drag some 2D panels to the second monitor I lose text on the primary monitor. Specifically, the text on the ATC menu, the text on the "parking brake warning" sign, and the text on EZLandmark (if I turn it on) flashes on and off, but not all the names. It seems worse with really complex panels (Aeroworx B200) yet the default panels seem to work. The sudden onset has me thinking the card is on its way out but can anyone think of another possible reason - preferably something fixable? ;-)Thanks!David