FPS Problem!

Hello!
I have:
Intel Core 2 Quad 2,4 GHz, 2 GB ram, Geforce 8500 256 mb ...
I have 15-60 FPS..
Before some patch ago it's working all.. But now.. I get that..
I get's sometimes errors and the game off..
When i play clan match after one round game off..

What it's going wrong?

I try witch all setings.. but nothing happen..