I know it says retail, but will it work with the Steam version?
You can send me the executable if it doesn't and I'll see if I can port it.
@Ivielios: What happens if you start the game first and launch the trainer while being at the main menu? Or does it crash after activation?
I get the .Net dialogue box if I activate it at menu or if I alt-tab from the game to launch/activate. Same result from staring trainer first then game, and vice versa. I also placed the trainer in the game's folder and made shortcuts of both the .exe and trainer, but activating it that way caused the game to lock up and crash.
Also, just sent the Steam .exe to you via PM. Hopefully that helps.