I was just touching off a group of tools and on the last one I noticed my Z position was around double what it should have been (machine position -30ish when it only has 20ish inches of travel). Machine returns to zero at top of travel, as if the scaling is off. This happened twice tonight. The second time I looked in the history and just before I set the last tool offset it said "license error 4".
The only way I found to recover from this issue is to restart Mach.