Trouble maximising video players and white screen scrolling down

[mavalon]

Hi everyone.

Since yesterday I've been having difficulties viewing videos in full screen with BBC iPlayer, Youtube and Dailymotion in both Chrome and Firefox.

As soon as I maximise the video in Youtube or Dailymotion, the screen goes completely black. It doesn't black out with BBC iPlayer, but the image freezes and the time bar renders strangely across the bottom of the screen.

Also, the screen has been going completely white when scrolling down on certain web pages, I have to refresh to get anything back.

Pretty bizarre. Any idea what this might be?

Thanks in advance!