So, I've played the first two episodes without any kind of save game corruption. Yesterday, I started a new game and something really weird happened on the first episode. I paused the game, and then every button (Resume Game, Settings, Main Menu and Exit Game) simply restarts from the beginning of it.
I have to force exit, and when I restart the game client, the save file is corrupted (I think so, because it won't load). I tried reinstall in different folders, cleaning the registry and today I was playing again, only to find the same problem.
It's the TTG version (not Steam) and on Windows 7 64-bit.