Hi,
I've made that mistake, its a real ba...rd!
Daz showed me a way of doing it...it was a while ago and I've all but forgotten how.
Open a CMD window and navigate to Mach4, I think run Mach4GUI.exe -p. The '-p' switch means that the program fires up in screen edit mode directly where you can dig the offending statement out.
Let us know how you get on, as I say its been a while...
Craig