I downloaded the the game files and RST file into an open game directory in the same WinPlan folder in which I play my C-M game. I have copied the same WinPlan directory to a new location, downloaded WinPlan 3.6.45, recopied the Reg.key file. I then redid my turn. Bad Turn message came back from the Host.
My games at C-M don't have the problem. I just did a .TRN file for a game at C-M and the turn was accepted.