I have ran Steam without problems for a long time, but relatively recently (not sure when or any changes made to cause the problem) any game I play on Steam will switch to Windows or minimise the game application approximately every 10 or 15 minutes. With most games this is an annoyance (pausing the game, or keeping the game running without pausing it), but some games will crash when this happens (Super Meat Boy). This problem seems to happen with every game I play using Steam, from Indie titles to AAA titles from varying publishers.
I've fiddled somewhat but can't seem to find any solution to this extremely annoying problem so any help would be appreciated. I am running on Windows 7 Ultimate 64 (and as far as I know this problem is not occurring with non Steam games, but maybe I should give one a good try when I get the chance). I doubt my hardware matters, but I am running a G77 Mobo with an i5 and a GT670 OC with 8GB of system RAM). Nothing appears to be popping up in Windows to activate teh switch either.