When I click the "System" button, the panel shows up fine. When I click it again to close the panel, or click anything that doesn't launch a process (all applications, computer, system, etc), the panel itself jumps up like 300 pixels and stays that way until I click the panel on and off a few times. I'm using compiz/xgl, and the panel is on the bottom left.
Before / after screenshots attached.
The actual order of the screenies is after / before. :-o