Flashy screen

[hopkiller]

Ok so i just got home a last night and i loaded up my favorite game TF2. Once in the game i started played, then i started to notice that the screen was lagging. I can tell it was not my connection. It seemed as it just was lagging up from the graphics card. My card is a HD 4850 at stock clocks. What should i do about it.

 

[copasetic]

Maybe there's a program running in the background chewing up system resources. Close anything that doesn't need to be running before you start the game. Check the task manager (ctrl+alt+del) for anything that looks unusual and post it here.

 

[hopkiller]

nothing else is running i checked that, but i have never had this problem before