Your Dad is a person, so he's who, not which.
Do you mean BT, or D0?
Have you tried the other BIOS bank? If the chip is on a pinheader, have you tried removing and reseating the chip?
When you say "I know there's nothing wrong with the Xbox hardware since it boots to the dashboard normally", do you mean that it boots to your hacked dash normally, but then FRAGs when you run the game, or do you mean that when you boot with the chip off it boots to the MS Dash normally but frags when you boot with the chip on?