Try checking the GPU temp when your playing. Could be your card overheating. Check the GPU fan and clean if there is dust. Try patching the game and also don't forget to update your video card driver
Why would my card overheat? its a new card, just bought it specifically for SC2. I played it for about an hour only then it freezes, tried it several times. My friend told me that its because of incompatibility, since i am using an old PC (a pentium D 820 bought last 2006) on a new card.
What do u guys think?