I've also run into this same error. I've used the method posted by caliber multiple times. I've even reinstalled the game. Nothing seems to be working.
A big +1
I enjoy my trainers in an offline style where i can do it when i need it!
I refuse to support anyone who abuses a trainer in a Online state!
if u still have the issue, it might be that u run with the Slayer as a bot because his special crashes the game if u have the option 3 enabled where it refreshes your special...