I was more concerned about it being a bios revision issue. The boot sequence is strange, as on the Jap mod system, it goes to the sega logo, then the satellite screen and then it either goes to CD player or Sega logo and hangs.
On the PAL system, it goes straight to the satelite screen, then the sega logo, then its fine.
On the jap saturn i think that the mod is causing it to go to the sega logo first and then stuffing up the rest of the process.
Whcih brings me to another point, what information does a mod chip return? I know it authenticates the CD's but does it just send a generic code back?