We have a Naomi here, but it's a straight-up ROM game, no GD drive... I'd check the cable connecting the main computer and the GD-ROM drive for any damage or wear, and reseat the connection on both ends. If that doesn't work... you have two of these, and one works, right? Swap the entire drive with the known working machine, keeping the discs with their respective machines. If that doesn't work, try swapping the cables.
If you're still at no dice, you probably have a problem at the computer side, either with the connector, or possibly board damage or a BIOS ROM error. Carefully inspect the connector on the computer for any signs of damage, soiled or burnt conductors, poor mating, the like. If you've gotten this far with no solution, verifying the BIOS ROM is worth a shot.
"Can not access GD-ROM drive" sounds like it can't initialize the drive in the first place, so it's probably not the disc itself... but I don't really know. If you swap the drives and get a different error, try swapping the discs.