SDK UnrealEd2 Problems

I start up my UEd2 (SDK), when I move an actor or a brush it just freezes at some point, the cursor dissapears, and after 3-4 secs, it reappears, and my camera is moved to the side a bit, and the brush/actor is moved to the side a bit. This happens everytime I move an brush/actor... Can anyone please help me out? Thanks.