powerbook g4 error msg, not sure what to do

its a powerbook G4 and when ever i start the pc up i get this msg

the msgs says

panic (cpu 0 caller 0x002de020: unable to find driver for this platform: "powerbook 5,6".

latest stack back trace for copu 0:
back trace 0x00095564 0x00095a7c 0x00026838 0x002de020 x002bd360 0x002bd118 0x002bdb80 0x002be1ec 0x00a9654

proceeding back via exception chain:
proceeding back state (sv=0x0051fa00
pc+0x00000000; msr=0x0000d030; dar 0x00000000; dsisr=0x000000000; lr=0x00000000; r1=-x--------; xcp=0x00000000 (unknown)

kernel version:
darwin kernel version 8.0.0 sat mar 26 14:15:22 pst 2005; root:xnu-792.obj~1/release_ppc
panic:we are hanging here

no debugger configured - dumping debig information
msr=00001030
latest stack back trace for cpu 0:

back trace same thing as aboove
proceeding back vi exception chain
pc+0x00000000; msr=0x0000d030; dar 0x00000000; dsisr=0x000000000; lr=0x00000000; r1=-x--------; xcp=0x00000000 (unknown)

anybody know what would cause an error such as this and how to fix it?

I would first try to boot into the Apple Hardware Test CD and check for hardware failure. If the hardware test passed then I would attempt to boot into single-user mood and run Applejack (or fsck if Applejack is not installed). That failing, I would boot the computer into target disk mode, access it with another Mac to backup the contents of my hard drive, then low-level format and re-install system.