Dakota, this must be the month for failing hard drives.
I have a beige G3 with two internal drives and one external. One of the internals is ATA and one is SCSI. The external is SCSI and is the problem. The two internals work fine. The external was working until I tried to move some system files from it to the ATA. Now it won't mount. The only thing that will see it is SCSI Probe and SCSI HD Setup. I ran a test on it with HD Setup and it tests fine. Disk Warrior and TechTool don't even see it. When I boot the system it locks up about half way through, cursor won't move, I turn off the drive and that frees the cursor although the boot does not continue. Booting with the drive turned off works fine. I've zapped the PRAM, rebuilt the desktop and deactivated all extensions and control panels, Yes All , to no avail. Any suggestions? I'm thinking of swapping the drive unit with the internal one to see what happens.