This is a common problem and sometimes really easy to fix. What you need to do first is, make sure all the weapons are set to on. Then make sure CrossHair Spread, Weapon Reciol, and Scope Drift are also on. This will fix the problem 75% of the time.
If that does not work, try reinstalling your game (full install) and leaving all the settings at default. If that works, then it is a problem with your settings in the game. If it does not work, and people keep getting punted, please seek profectional support from
http://www.novalogic.com