External Firewire Drive Won't Mount

[tompaine]

My Mac is a G4 AGP Graphics upgraded to OS 10.4.11 with a 1.2 GHz Sonnet processor and 1.5 GB RAM. My external Firewire drive suddenly stopped mounting after working fine for a couple of years. The computer has no other issues with everything else working normally.

Disk Utility sees the drive as does System profiler: (ST3300631A:

Manufacturer: Initio
Model: 0x0
GUID: 0xBC203000413B7
Maximum Speed: Up to 400 Mb/sec
Connection Speed: Up to 400 Mb/sec
Sub-units:
ST3300631A Unit:
Unit Software Version: 0x10483
Unit Spec ID: 0x609E
Firmware Revision: 0x407
Product Revision Level: 4.07
Sub-units:
ST3300631A SBP-LUN:
Capacity: 279.46 GB
Removable Media: Yes
BSD Name: disk4
OS9 Drivers: No
S.M.A.R.T. status: Not Supported

Disk Warrior successfully rebuilt the directory but the drive still won't mount. In Disk Utility the "Mount" command is grayed out.

The issue first arose when I tried to change the access to the disk for a "standard" user on my Mac - the only other account on the Mac. In her account I changed her access to none. The disk icon disappeared. When i switched back to my admin account the drive icon appeared but when I clicked "Get Info" is falsely said there were zero items on the disk, then the icon vanished!

Disk Utility sees the disk, the disk checks out as undamaged. Disk Warrior sees it, too, but it will not mount - (the icon won't appear on the desktop). Other Firewire devices work in the same port.

I haven't been able to get it to mount again, despite numerous restarts and one firewire "reset" by shutting down, disconnecting and reconnecting the drive. Any ideas on how to get this drive to mount?