Norton 360 affecting my video game graphix!

hi! i just bought and installed my new norton 360 yesterday and right after that my pc game graphics always giving errors. It slowed down my pc performance, my game always get disconnected or it crashes, and some graphic files are missing. I tried disable the norton 360 and it went back to my normal gaming, smooth and im not getting disconnected. what seems to be the problem?? what can i do? pls help.. thank you.