I have a model 1 genesis and model 1 sega cd and Mortal Kombat freezes at the sonic the hedgehog screen. It is my understanding that some model 1 units had Sony drives and some had JVC drives. Mortal Kombat works fine on Sony units but has my problem on JVC units. Apparently Aklaim would send out a different disc if you told them you had the JVC problem. I am wondering if there is a way to tell the difference by looking at the disc? I have tried 4 copies thus far with no luck. If anyone has a copy that will work for me let me know.