Something very, very odd with the elements in window screens

by Jollesax
(Belgium)

For almost a month now, I see this happen regularly: one window screen suddenly shows elements of a window underneath (see the screenshots). I didn't have this before. It's noteably often when using R and Chrome, but it's not limited to that combination (I just have these windows open very often).

If this happens (and that's always when I'm busy on the other screen), i can hover with my cursor over the screen to show some original elements again. But not everything. This is shown in the file below. The other file shows the R window on top, so you can see where the element comes from.

I run Windows7 64bit, completely updated, with a double screen.

I also noticed that on a HP the taskbar can get a box suddenly where the HP help center link should be, and often this box is containing some graphics from another window that has been opened.

Please fix.