The Trainer should work also with the Steam version.
Try the following.
Sart the game using Steam then switch back to desktop and start the trainer.
Now select Mass Effect 2 and the matching version and click on the start button at the top of the trainer window.
Now the cheats should work.
If not then please provide us the md5 checksum of your masseffect2.exe file.
Thank you for your reply. I started the game via steam, got all that ready, alt-tab'ed out to the desktop, and tried using the trainer, but the same error message appeared, "Error Starting Game."
After using CheckSum, here are the results...
MassEffect2.exe - 16f214ce81ba228347bce7b93fb0f37a
MassEffect2Launcher.exe - e4ea94231e17279c69b415813103e629
I see that this doesn't match up with what is on file here, but that doesn't make sense, since Steam automatically (and has) updated the game to the latest patch, 1.02.