MacBook Pro 15.4" Screen Flickering on Blue/Gray Gradient Images

Hello,

I bought used MacBook Pro 15.4" (2010 model) about a month ago. In 2-3 weeks, I didn't realize that my screen was flickering. Now I realized that. It really made me upset. 😟 I asked billing/guarantee information but they said "We bought it on e-bay. We have no billing/guarantee information for that product."

I tried EVERY way to fix this problem.

Tried to;

- Upgrade my video card driver. (Nvidia GeForce 9400M)

- Resetting PRAM (Holding Cmd+Option+P+R before booting)

- Changing Refresh Rate with SwitchResX Control.app

- Software Update (Already have 10.6.7)

Sorry for my bad English.

Please, anyone can help me?