hmmm... if u patched the game to 18.104.22.168 which im guessing u already did since ur in this forum here's a couple things u could try.
1. download and Update everything incl. Game for Windows Live! 2. If using Vista run the trainer as Administrator.
Well those r the only 1's i can come up with .
I did those 2 things suggested by P.Wizard and it seemed to work after that. Might've been just the administrator thing not really sure tho but i re-downloaded the trainer after all that and it worked.