I also have a 3x monitor setup and get the same error.
When I move the trainer window to my left monitor, the [X] to close the program do not work so I have to use the close program via the icon on my taskbar. This results in a "The following error happened: Invalid memory access--> Error #3110"
And a .debug notepad file comes up with this info:
"Trainer Starting
Witcher 3
Debug Info located: C:\Users\--\Cheathappens\Debug\Witcher 3.debug
Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
x64 Trainer
Windows 8 64bit Operating System
Setting Up GUI
No Joystick detected.
Waiting for Trainer Activation
The following error happened: Invalid memory access-->Error#3110"
if you move it back to your main screen the buttons work again, having the same issue for a while now with the trainers