If you are trying to use it with the Steam download version, it will not work. The trainer is almost 3 years old and was only writtent to work with the commercial version. I dought they will create a new or update for the Steam download.
WRONG! The game does not crash with the 1. METRO 2033 MEGA TRAINER (PATCH #2) on steam.
I have the STEAM version when I played the game for the first time the trainer worked fine. Now going back to play it, it crashes everytime.
What crashes the trainer? the game? which os you are using?