AMD A6-3500 Llano issue

I have a Home Theater PC with the following components:

AMD A6-3500
Asrock A55M-HVS Mobo
4GB Kingston DDR3 SDRAM
Zalman CNPS8900 Extreme
Windows 7 Professional

I am using the GPU on the Llano APU.

I have the system overclocked by increasing the FSB to 124 MHz. I have run memtest86 overnight with 10 passes and there were no errors. I have run all 3 torture tests with Prime95 overnight, as well, without any errors. The max CPU temperature during any test is 43C.

However, I have been having one problem. The graphics glitch out sometimes, requiring a reboot to fix the problem. I'll try to describe what this glitch looks like, as best I can. I have the Windows 7 taskbar set to auto-hide, at the bottom of the screen. When the glitch occurs, the little sliver with the taskbar moves to the top of the screen. Also a couple black boxes appear on the screen, one near the start button and one in the center of the screen. They're not totally black in that they form some sort of hatch-type pattern where it is mostly black, but there are parts where you can see the original Windows 7 background.

The graphics have only glitched out since I overclocked the system. I'm not 100% certain, but I think they have also only glitched out when I have been running an emulator (Project64 and psx1.13).

The question I have is: Does overclocking the FSB increase the clock frequency for the GPU as well? Could this be the source of the problem? Or does this issue sound like it has another source?