Startup Apple and bar Distorted, Then gray screen

Hi

Surfing the internet my screen turned suddenly all white. Nothing was displayed anymore. I forced my MBP (early 2011) to shut down by holding the powerbtton.

On statup the Apple Logo and progressbar are distorted. But the progressbar dows work. After it's about half way I get a gray screen and thats where it stops. Safemode dosn't work.

Any thoughts?

Thanks.

Gerard