I don't know if this has anything to do with the issues I've read about with the patches, but here's the issue:

Didn't play at all for about three weeks. Fired it up again about a week ago and the picture was very jerky, difficult to focus on anything. FPS issues? After trying to play it a few times, I have decided that's not the problem at all.
If I'm at a standstill, everything looks fine, video is just as it's always been. It's the mouse, when I am moving or especially when running, the control seems very loose and unpredictable, it's hard to get the mouse on a particular spot (even when clicking on load, etc) and the picture just flies all over as a result. The game used to run perfectly, now it's nearly unplayable - I go to hit someone and the camera flips up to the sky, it takes me a minute or more to click on something in particular and by then I am under attack or walking off a cliff. Help! Mouse action, btw, is perfectly fine outside the game.


Windows 7
No mods
updated GPU drivers (didn't help)