Vsync Screen Tearing / Scan Line Issue?

This is something I noticed on my iMac after updating to Mac OS X 10.6 Snow Leopard. I noticed a horizontal break in the screen when I was doing any kind of graphic intensive operation. Anything from scrolling up and down on a web page in Safari, to switching screens in Spaces, to bring up my Dashboard or switching users with FUS. By opening a new movie recording in Quicktime X and simply moving the video around, you can clearly see this break is not a random screen tear, but actually some sort of scan line moving from top to bottom in my monitor. I've never seen this prior to Snow Leopard, but I suppose it is possible this is a hardware issue, rather than a software or driver issue. Can anyone else duplicate this on Snow Leopard? I am on a 2007 2.8 Core 2 Extreme iMac with RadeonHD2600 graphics.

I made a video of the issue and posted to youtube if you want to see what I am talking about.

http://www.youtube.com/watch?v=0u2BIubdGu4

Message was edited by: Danny Z