Hi, Carl
Do the other menus open up under "Config" pull-down list ? (Could have a password set under Operator if none of them will open).
If it won't open the "motor tuning" window only in Mach3, (I've had this happen several times in the past) You'll need to reinstall Mach3.
Make a copy of your Mach3Mill.xml or what ever it's named (profile you load/run with Mach).
It's located in C:\Mach3 folder (standard install for Mach).
Hope this Helps, Chip