Ouch, that is really bad news. Did the move with the error involve the cutting of an arc, by any chance? If it did, there most likely was a mathematical error in the calculation of the end point of the arc, or the arc center coordinates.
Do you already have a favourite cadcam system? Usually, there are a few options to set in the post driver having to do with the arc format. Might be something to check.
Like Mortek said, give us a glimpse of your code.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)