Chunks of tooltips get stuck, where the screen isn't refreshing, I guess. (Windows 7 Professional x64, 1-2 monitors)

Problem

Here's a screenshot: It happens a lot, not always. This screenshot was taken after less than an hour of browsing web, searching for something desperately, a lot of mouse movement, plus working on something else, don't remember what software. If I'd press start, for example, the whole top area would…