Well it just did it!!!!!!!!!! Fortunately it was on a drill program, so all it did was drill some holes in the wrong place. Worked ok for one set of parts then acted liked got lost on the second set.
it seems to be the Y that losing location.

A pic would help to see what you are working with. You can use the additional options button on the reply page to attach. You may have tro reduce the file size, a good programme to use for that is screenhunter by Wisdomsoft, there is a free version.
Hood