I was running a fairly simple program today and the machine appears to have skipped over two G1 commands. The reason I say skipped commands instead of skipped steps is that when I checked the machine location after the program ran, it was off by exactly .5" in X. The program was taking .25" steps in X, so this would be consistent with skipping over two G1 commands. This has happened once or twice before in the past couple of months. It is not repeatable, and it is not an error in the program, since I can run the program again and get a correct cut (as well as run it in OpenSCAM and get a correct visualization).
Any thoughts on how to prevent this in the future, or at least confirm this is the problem?
I'm running Mach3 on a Core 2 Duo Windows 7 machine, talking to the router via a USB controller board.