It seems to be doing this more regularly recently. It's done it twice today so far; I'm not playing any games, and it seems to be doing it at random intervals (but it doesn't happen often). This is a static photo of it as it was 'moving around', so to speak [can't explain it].
On a side note which may be related, is that my monitor sometimes adjusts its resolution to something else while still keeping its 1280x1024 res (from what I've read happens from a Google search) - the screen goes blank for a second, the the desktop text looks very slightly blurred/out of focus.
Could my graphics card (or monitor) be on its way out?