Recently I had a problem where my mouse would jerk and snap to look at the sky or the ground while playing games such as Crysis, Borderlands and Battlefield 2 (these are the only games I tried). Anyway after much trial and error and searching, it turned out to be the fact that I had iz3d drivers installed, used for stereoscopic gaming. Simply disabling 3D didn't fix it, neither did exiting the progam, but once I uninstalled it the mouse snapping problem was fixed!
Hope this helps someone else.
