I have tried running several g-code examples in Mach 3. The first time after running Mach 3 and loading the code, it seems to run just fine. After rewinding and restarting the same code cycle, sometimes the x-axis will inexplicably change the scaling to -1 (scale "LED" flashes and displays -1. A few of the initial cuts may start out ok but then it suddenly reverses and all subsequent cuts are mirror imaged wrt the x-axis. Rewinding and trying again gives the same behavior. Manually resetting to +1 doesn't seem to cure it.

Any ideas on what I am doing wrong?