When creating a zip2go, if you get this warning before it populates, there is a solution :
Go into REGEDIT and find HKEY_CURRENT_USER\SOFTWARE\CNC Software, Inc.\Mastercam [VERSIION] and delete what ever version is giving you the problem.
When you restart Mastercam, it will recreate this folder and correct any weirdness that caused this error. This is a good trouble shooting method for many errors that have to do with bad files in the background.