Program freezing

Very new at this. I have an UNO board GRBL 1.1 Use UGS Platform to send gcode to my CNC. After a program run is complete, the program locks. Have to use task manager to terminate UGS. If I delete all the UGS folders, I can sometimes home the machine after a cut but cannot run a new file. Fresh install of Windows 10, did the same with XP and Windows 7. I did erase and reload 1.1. Using M0 or M2 does not change anything. I'm at a loss, dozens of users of this machine and software combo have no problems. Help!

I had a similar problem when i first used Grbl. There was a g code in the header (written by a G code generator program) that stopped Grbl (G91.1 I think). Check the header and footer of the G code file for unsupported codes.