Occasional video distortion when awaking from sleep. Pre Snow-Leopard it would be just the mouse cursor which would turn into some weird distorted block with stripes and such. After upgrade to Snow Leopard things worsened *a lot*. When awaking from sleep the computer will show the display as if the sync is entirely wrong, or more likely as if you're looking at some far-away television channel during a thunderstorm. The desktop is shown actually but many pixels just go crazy by moving several inches left and right extremely quickly, resulting in horizontal lines. The computer won't freeze but I'm pretty scared to trash my ATI adapter. This is not temperature related as this does even happen when awakening the MBP the next day.
Rebooting the laptop does solve the problem. Even getting the MacBook pro into sleep again and then awakening it again does solve the problem. I don't think this is a hardware problem, it's software, driver related (ATI X1600).
BTW it doesn't matter if an external display is attached or not. But, the glitches do not appear on the external display.
MBP 2.2 (Core 2 Duo 2.16 GHz / 2 GB / 120 GB), Mac OS X (10.6.1)