Crash panic G5


I'm new here and looking for help. I have seen people diagnose faults by looking at the crash report but sorry to say that I have tried to follow what was going on and found myself lost.
I have a G5 that randomly shows a grey screen with a message to shut it down. It happens perhaps twice in a day or once in a week.
I have reinstalled Leopard and updated all suggested stuff but to no avail.
This is the crash report from the latest crash.

Interval Since Last Panic Report: 0 sec
Panics Since Last Report: 1
Anonymous UUID: 167D0D04-DECB-48CF-8A8A-AC4B31CFE434

Sat Aug 4 21:17:02 2012
panic(cpu 1 caller 0x000AD128): simple lock (0x069EE7D4) deadlock detection, pc=0x00030AC8

Latest stack backtrace for cpu 1:
0x0009CC88 0x0009D63C 0x00029DA0 0x000AD128 0x00030AC8 0x000AC898 0x000251A0 0x000B45CC
Proceeding back via exception chain:
Exception state (sv=0x6e841c80)
PC=0x8FE20B88; MSR=0x0000D030; DAR=0xBFFFB700; DSISR=0x42000000; LR=0x8FE203E0; R1=0xBFFFB4B0; XCP=0x00000030 (0xC00 - System call)

BSD process name corresponding to current thread: ReportCrash

Mac OS version:

Kernel version:
Darwin Kernel Version 9.8.0: Wed Jul 15 16:57:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_PPC
System model name: PowerMac11,2

System uptime in nanoseconds: 185320826179
unloaded kexts: 2.5.8f1 - last unloaded 4335715108
loaded kexts: 2.5.8f1 - last loaded 1105442452 2.5.8f1 5.4.8 1.0.6 5.4.8 2.5.8f1 3.4.0d0 2.5.8f1 1.9d0 2.0.2 1.3.2 1.9d0 2.5.8f1 1.9d0 1.7.7 1.7.2f1 1.9d0 1.9d0 1.9d0 1.0.1f1 1.5.2d0 1.1.1d2 1.1.0 3.4.6 3.2.0 2.1.1 2.1.1 2.7.91 2.0.6 3.4.9 3.4.9 1.5.3 1.0.4f2 1.3.0d0 1.3.0d0 1.5.3 4.0.0d2 1.1.1d2 3.9.7 1.2.1f4 1.0.5b1 3.4.6 3.4.6 1.7.2f1 2.2.3b1 1.2.1d1 3.4.0 1.1.1 1.0.5 107.12 1.6.77 3 30.4 199 2.0.4d9 2.5.8f1 2.5.8f1 5.4.8 1.7.3 1.7.3 9.4 2.5.8f1 2.5.8f1 2.5.8f1 1.6.9fc5 1.1 3.4.0d0 3.4.0d0 3.4.0a17`

Is it one of the processors?
I have read about rearranging the ram, removing graphics cards and faulty hard drives but would seriously welcome a bit of guidance as to where to start.

Here are some details about the mac

Hardware Overview:

Model Name: Power Mac G5
Model Identifier: PowerMac11,2
Processor Name: PowerPC G5 (1.1)
Processor Speed: 2.3 GHz
Number Of CPUs: 2
L2 Cache (per CPU): 1 MB
Memory: 5.5 GB
Bus Speed: 1.15 GHz
Boot ROM Version: 5.2.7f1
Serial Number (system): CK5440TFR6V
Hardware UUID: 00000000-0000-1000-8000-00145163E8BC

NVIDIA GeForce 6600:

Chipset Model: GeForce 6600
Type: Display
Bus: PCIe
Slot: SLOT-1
PCIe Lane Width: x16
VRAM (Total): 256 MB
Vendor: NVIDIA (0x10de)
Device ID: 0x0141
Revision ID: 0x00a4
ROM Revision: 2149
VGA Display:
Resolution: 800 x 600 @ 60 Hz
Depth: 32-Bit Color
Core Image: Hardware Accelerated
Main Display: Yes
Mirror: Off
Online: Yes
Quartz Extreme: Supported
Rotation: Supported
Display Connector:
Status: No Display Connected


easiest place to start is gut everything take out all but the boot HDD take our all PCI cards (leave graphics card) remove all RAM. Start by putting in only one stick of ram and boot it with only the boot drive and a stick of RAM also unplug the data and power cables off the DVD drive.