Call of Duty 6 – Crosshair shutters

Its really strange problem , but my crosshair shutters when i play.It doesnt go smooth like it needs , it shutters like hell.My ping is <70 and fps about 50.Please help , its impossible to play , i cant aim anyone.I play games like WoW , Dota , CS and everything goes OK
Answer #1
You mean Lag? In MP?
Answer #2
It doesnt lag.I cant explain what it is , crosshair shutters , it doesnt go smooth.Its impossible to aim