Quote Originally Posted by dazp1976 View Post
I had a PC that would knock / lose steps on every 360 degree rotation of the screw on every axis.
I re-installed windows and the issue was gone.

It was an error with NT driver in windows that came up every so often.
When I first had this fault I did try a completely different PC and it didn't solve the issue. On the other hand if the problem was as consistant as yours it may be easier to solve.