2 disc game..

[Kendomon]

A Mod chip shouldn't have a problem. Are you also using a game enhancer our some device that requires the lid sensor to be pressed down at all times? Most games just need and indication that the lid has been opened so if your using a spring, simply lift up the end that is holding the sensor down and then put it back, once the game thinks the lid has been open it will move on.

Also check and see if there is a chance to save before going on to the next disk, a game save at the end of a disk can usually be read by the next disk, simply power off the machine and start the next disk and load the save file.