When im playing tf2 (or any other game) randomly it will freez up requiring a ctrl-alt-del. Upon returning to the game my mouse will be laggy and my fps will be half of whatever my fps cap is (so if its 240 i get around 120 fps, if its 60 i get around 30 fps…) and the only way to fix this is restarting the pc.

specs:
560ti MSI Oc edition
i5 2500k
windows 7 64
nothing is overclocked

this makes me sad when im playing an important game or in the middle of startcraft. any1 got any ideas?