Kernel Panic/Restart message on my Power Mac G4

I recently acquired a QuickSilver 2002 Dual 1GHz model running Mac OS X 10.4.11, and it's been running about four days with no problems- that is until today, when I started getting this kernel panic message (follow down to the bottom to continue):

Unresolved kernel trap(cpu 1): 0x300 - Data access DAR=0x0000000000000000 PC=0x0000000000473460
Latest crash info for cpu 1:
Exception state (sv=0x2D5EA780)
PC=0x00473460; MSR=0x00009030; DAR=0x00000000; DSISR=0x42000000; LR=0x00473444; R1=0x17673C80; XCP=0x0000000C (0x300 - Data access)
Backtrace:
0x00473444 0x00530570 0x002EC058 0x0008C69C 0x00029234 0x000233F8
0x000ABEAC 0x00000000
Kernel loadable modules in backtrace (with dependencies):
com.griffintechnology.iokit.PowerMate(1.6.4)@0x52e000
dependency: com.apple.iokit.IOUSBFamily(2.8.1)@0x467000
dependency: com.apple.iokit.IOHIDFamily(1.4.13)@0x4a9000
com.apple.iokit.IOUSBFamily(2.8.1)@0x467000
Proceeding back via exception chain:
Exception state (sv=0x2D5EA780)
previously dumped as "Latest" state. skipping...
Exception state (sv=0x39E66000)
PC=0x9000B348; MSR=0x0000D030; DAR=0xF0080EC4; DSISR=0x42000000; LR=0x9000B29C; R1=0xF0080BD0; XCP=0x00000030 (0xC00 - System call)

Kernel version:
Darwin Kernel Version 8.11.0: Wed Oct 10 18:26:00 PDT 2007; root:xnu-792.24.17~1/RELEASE_PPC
panic(cpu 1 caller 0xFFFF0003): 0x300 - Data access
Latest stack backtrace for cpu 1:
Backtrace:
0x000954F8 0x00095A10 0x00026898 0x000A8204 0x000ABB80
Proceeding back via exception chain:
Exception state (sv=0x2D5EA780)
PC=0x00473460; MSR=0x00009030; DAR=0x00000000; DSISR=0x42000000; LR=0x00473444; R1=0x17673C80; XCP=0x0000000C (0x300 - Data access)
Backtrace:
0x00473444 0x00530570 0x002EC058 0x0008C69C 0x00029234 0x000233F8
0x000ABEAC 0x00000000
Kernel loadable modules in backtrace (with dependencies):
com.griffintechnology.iokit.PowerMate(1.6.4)@0x52e000
dependency: com.apple.iokit.IOUSBFamily(2.8.1)@0x467000
dependency: com.apple.iokit.IOHIDFamily(1.4.13)@0x4a9000
com.apple.iokit.IOUSBFamily(2.8.1)@0x467000
Exception state (sv=0x39E66000)
PC=0x9000B348; MSR=0x0000D030; DAR=0xF0080EC4; DSISR=0x42000000; LR=0x9000B29C; R1=0xF0080BD0; XCP=0x00000030 (0xC00 - System call)

Kernel version:
Darwin Kernel Version 8.11.0: Wed Oct 10 18:26:00 PDT 2007; root:xnu-792.24.17~1/RELEASE_PPCModel: PowerMac3,5, BootROM 4.3.3f2, 2 processors, PowerPC G4 (2.1), 1 GHz, 1 GB
Graphics: NVIDIA GeForce4 MX, GeForce4 MX, AGP, 64 MB
Memory Module: DIMM0/J21, 256 MB, SDRAM, PC133-333
Memory Module: DIMM1/J22, 256 MB, SDRAM, PC133-322
Memory Module: DIMM2/J23, 512 MB, SDRAM, PC133-333
Modem: Spring, UCJ, V.90, 7.0F, APPLE VERSION 0007, 7/31/2000
Network Service: Built-in Ethernet, Ethernet, en0
PCI Card: usb, usb, SLOT-3
PCI Card: usb, usb, SLOT-3
PCI Card: pci1735,e0, SLOT-3
Parallel ATA Device: WDC WD5000AAKB-00YSA0, 465.76 GB
Parallel ATA Device: Maxtor 6Y080P0, 76.33 GB
Parallel ATA Device: PIONEER DVD-RW DVR-109
USB Device: Hub, Up to 12 Mb/sec, 500 mA
USB Device: CanoScan, Canon, Up to 12 Mb/sec, 500 mA
USB Device: Studio Display, Up to 1.5 Mb/sec, 500 mA
USB Device: Hub in Apple Pro Keyboard, Mitsumi Electric, Up to 12 Mb/sec, 500 mA
USB Device: Apple Optical USB Mouse, Fujitsu Component, Up to 1.5 Mb/sec, 100 mA
USB Device: Apple Pro Keyboard, Mitsumi Electric, Up to 12 Mb/sec, 250 mA
USB Device: General Purpose USB Hub, Up to 12 Mb/sec, 500 mA
USB Device: Griffin PowerMate, Griffin Technology, Inc., Up to 1.5 Mb/sec, 500 mA
USB Device: GD-0912-U, Tablet, Up to 12 Mb/sec, 500 mA

I think it has something to do with the Griffin PowerMate (it's a silver metal knob that's multi-programmable); it was the last thing I installed today, and the G4 was running fine before this. Can someone decipher this error message and confirm this for me? Thanks!