Help!! can anyone decipher this error report?

Question

I would be really grateful if anyone could decipher this error report. My system has become really unstable and unusable if I can get beyond the grey screen. During use I get a grey curtain come down and a message telling me to hold the power switch to shutdown.
Model: MacPro1,1, BootROM MP11.005C.B08, 4 processors, Dual-Core Intel Xeon, 3 GHz, 2 GB
Graphics: kHW_ATIr580Item, ATY,RadeonX1900, spdisplayspciedevice, 512 MB
Memory Module: DIMM Riser A/DIMM 1, 1 GB, DDR2 FB-DIMM, 667 MHz
Memory Module: DIMM Riser A/DIMM 2, 1 GB, DDR2 FB-DIMM, 667 MHz
Running 10.5.5
PCI Card: ATY,RadeonX1900, display, Slot-1
One of the many messages reads:
Mon Sep 29 21:59:41 2008
Machine-check capabilities (cpu 3) 0x0000000000000006:
family: 6 model: 15 stepping: 6 microcode revision 198
Intel(R) Xeon(R) CPU 5160 @ 3.00GHz
6 error-reporting banks
Machine-check status 0x0000000000000005
restart IP valid
machine-check in progress
MCA error-reporting registers:
IA32MC0STATUS(0x401): 0x1000000020000000 invalid
IA32MC1STATUS(0x405): 0x0000000000000000 invalid
IA32MC2STATUS(0x409): 0x0000000000000000 invalid
IA32MC3STATUS(0x40d): 0x0020000000000000 invalid
IA32MC4STATUS(0x411): 0x0000000000000011 invalid
IA32MC5STATUS(0x415): 0xb200001080200e0f valid
MCA error code : 0x0e0f
Model specific error code: 0x8020
Other information : 0x00000010
Status bits:
Processor context corrupt
Error enabled
Uncorrected error
panic(cpu 3 caller 0x001A8656): Machine Check at 0x00ba9e07, thread:0x3efce40, trapno:0x12, err:0x0, registers:
CR0: 0x8001003b, CR2: 0x00000000, CR3: 0x01009000, CR4: 0x00000660
EAX: 0x00000000, EBX: 0x00000000, ECX: 0x00000004, EDX: 0x2855a240
ESP: 0x2e5f3820, EBP: 0x2e5f3888, ESI: 0x03e41d00, EDI: 0x03e1f000
EFL: 0x00000002, EIP: 0x00ba9e07
Backtrace (CPU 3), Frame : Return Address (4 potential args on stack)
0x2e676fb8 : 0x12b0fa (0x459234 0x2e676fec 0x133243 0x0)
0x2e677008 : 0x1a8656 (0x462498 0xba9e07 0x3efce40 0x12)
0x2e6770e8 : 0x19fcf3 (0x2e677100 0x0 0x0 0x0)
Backtrace terminated-invalid frame pointer 0x2e5f3888
BSD process name corresponding to current thread: kernel_task
Mac OS version:
Not yet set
Kernel version:
Darwin Kernel Version 9.5.0: Wed Sep 3 11:29:43 PDT 2008; root:xnu-1228.7.58~1/RELEASE_I386
System model name: MacPro1,1 (Mac-F4208DC8)
Many thanks guys.

Answer 1

Firstly, well done for getting the crash log.
The bit :
+Processor context corrupt+
+Error enabled+
+Uncorrected error+
+panic(cpu 3 caller 0x001A8656)...+
I'd say is the immediate cause (kernel panic) of the shutdown.
Apart from that, is your memory ok?
There was an identical (is that you\?) post a while back on:
http://forums.macrumors.com/showthread.php?t=484526
This article gives some mmore info as to possible resolution:
http://support.apple.com/kb/TS1388?viewlocale=en_US
Antoher poster had problems with 1st gen Mac Pros:
http://discussions.apple.com/thread.jspa?threadID=1722821&tstart=0
Finally, and this is probably your best course of action: *phone apple (if you cannot get into an Apple store).* It sounds serious enough to me.
Sorry I could not help any further. Good luck