Problem on steam games. help?

My steam games are freezing from 3 to 5 seconds and come back. its unusual but only steam games do this. and its not the lag, even on single player it keeps freezing, I have a great notebook, and it can run perfectly Team Fortress 2, garry's mod , and Left 4 dead, I checked on "can you run it?". the frezzing is like, during the game the whole screem and sound stops for 2 to 5 seconds, and when it comes back I am standing still. If I was typing during that, everything apears, but if I was walking or shooting it wont do it. plz anyone help?