I have the same problem. When I played for the first time last night, it worked perfectly. Now, I get stuck in a loop of receiving the error message below, then being sent back to the "Press the Start button" screen.
This happens when I try to load my profile or create a new one, so the game is unplayable unless I create an offline profile. I've deleted my save data from My Documents and my profile on the TDUWorld site, uninstalled/reinstalled the game, and nothing seems to fix it.
I have a non-Steam online activation code and the RU version of the game.
If anybody knows anything about this and could help us out, that would be awesome
Thanks!
Edit: I found another post that mentioned it was solved by adding the key.txt file with the activation code to the game directory. I already have it in there with my code, so I'm not sure what else to do.