I just started getting these weird, black vertical bars this morning. I did some searching and it may be the ATI9800 card. I have a dual G5 PowerMac. Repaired permissions and ran all the updates. I tried restarting a couple of times too. The black bars are pretty much where graphics are: they follow the mouse pointer, behind icons, on the edges of windows, etc. They don't seem to affect performance though or obscure the main portion of windows (e.g. Safari), which is good. Anyone seen this before?