I didnt say to turn off the controls in steam, i said to turn off the desktop configuration. Steam allows you to control the desktop by using a controller as a mouse, and maps the keyboard arrow keys to the left stick and enter on the A button. This is what is interfering with Bigbox. You can just disable steam having control on the desktop, all normal controls will still work in games, you will just lose the ability to do normal desktop things with the controls on your cabinet, which im guessing you dont want to do anyway.