I've got the exact same problem. Strangely enough, my friend who bought an almost identical computer at the same time does not. Because of this I had thought my graphics card was the culprit... but you had this on two completely different set ups so I guess not (although it's still possible, however unlikely).
Edit, forgot: My hard drive was defective and gave up after a week so I had it replaced. Installed everything from scratch again. The glitch was present in both installs of windows.
Windows 7 Ultimate (64-bit)
Radeon HD 5700: Catalyst 10.2 (same when I had 10.1)
One more difference maybe. I'm using wide-screen screen, 1680*1050. If memory serves, my friend has 1280*1024.
Another picture, showing only one "step" glitched out...