Hmmmm.... that is.... fascinating...
Okay, there might be a reason for that. And that is your mouse pollrate. I'm not sure how exactly to fix it if that is the problem, so we'll have to work together on this one.
Try to use a different mouse for starters. That would eliminate at least one reason for this problem to occur.
Also, check if frame limit is enabled (set to 60). A very high framerate might also cause this problem.