Wow, never heard of this one, can you possibly take a video showing this, or possibly give a step by step detailed picture of what's happening on the machine and what shows in Mach 3 when it is happening?
Is it completely jumping the part to another part altogether? If not, maybe your depth on that particular part is not set properly in the CAM program?
I'm sure one of the pros here will help, but that is definitely first for me.
Dave