I think I understand the problem. The steam version is version 1.06.2011. If you use the windows 8 compatible trainer, then you have to use the 07.04.2011 trainer. The trainer for 1.06.2011 is not windows 8 compatible. Unfortunately, I think Caliber said somewhere in this thread that he can't make the 1.06.2011 trainer windows 8 compatible because he can't roll back to the 06 patch. So the only trainer windows 8 compatible is not the version steam uses. I don't know why they rolled back.
All I can suggest is that you find the patch for 07.04.2011 and update the game manually. I'm not even sure if that would work.
Hope some of this made sense and good luck.
the "DEAD RISING 2 ULTIMATE TRAINER (RET+DIG 01.06.2011)" stopped working instantly (running as admin)
im using win 7 x64