I run a dimension 5150 which came with a Dell optical mouse(wired).The pointer behaved erracticily (it would jump and move around the  screen despite having disabled all mouse "smart" actions)so I changed the mouse to a logitec  optical mouse that I happened to have-same problem.This I believe is not a windows software problem as the same thing happened under Linux on the same PC.

 

I thought I would try a mechanical mouse but instead ended up buying a wireless mircosoft optical mouse which behaves great.Problem resolved.