You the man, Curtis. I hadn't considered cleaning the board prior to testing. I'll give it a shot. The board support might actually come in handy as well; I've got relatively small PCBs, but thinking back, the do flex a bit during the testing. I hadn't thought it would be enough to interfere with the prober connection, but then, maybe it does. I'll give it a shot.
I'm a bit disappointed at the lack of real pick-up for this forum. I really thought there would be more involvement by now.