Not sure if this will work or not... I just noticed that we have a new trainer update for Batman. Since steam likes to update as quickly as the trainer comes out I decided to unplug my computer from the internet, I started steam but with out the connection it will only start in off line mode, I tried to change the automatic update but it wont change in offline mode so I continued to start Batman. No updates were done to the game, GFWL started up and let me then continue to start Batman. I have no clue if this will affect saves but my thought was to try to stop the update which this way seems to do. I'm going to unplug my computer from the internet again and see what happens when I try to run the game with the trainer... will report back!
Never mind that! The computer needs to be on line in order for the trainer to even work. I was able to start it by leaving my computer connected to start the trainer and then unplugging it once the trainer started. Started the game with no problem and GFWL but as soon as I tried to use num pad 1 key the game crashed with some sort of QA error message. I restarted the game with out the trainer still unconnected to the internet and it worked so I have no clue from here. I do believe that if I start steam on line it will update Batman again and will once again render the trainer useless so any guess is as good as mine... Sorry, I tried!