after an update on wednesday I got some serious problem with flash. Whenever I watch a video clip on sites like youtube, the video somehow stays in the background and "shines" through any black field in applications. So videos look shattered, but it is even worse for texts - they are almost unreadable on the part of the screen where the video was. This doesn't show on screenshots though.
I un- and reinstalled flash a couple of times now, tried another video-driver, but it didn't help.

Any thoughts?