Hi, I have the same problem with my game, purchased in Gamersgate. I have followed all steps related with DEP and programs like antivirus, etc. but I cant launch CMSF when I install 1.21 to convert the game.
For the moment, I will keep version 1.20. I'm thinking about purchasing CMSF in BFT store, but such situations are a bit frustrating for legal owners of games.
Andrés.