Multiple crashes, mainly on start-up

Question

Hi, I have been getting kernel panics, mainly during or directly on completion of start-up but also occasionally a few minutes later. Although this has been going on for a very long time I always try restarting a few times until all appears well and can then almost always work for many hours - even days at a time. On switching off and restarting the problem almost invariably returns.
I just contacted Apple support who told me how to find the panic information log but they suggested I back up my data and start from the beginning. They said it is most likely to be a software problem.
It is easy to say re-format and re-build but that's an immense task so I hope there's someone who knows how one can attempt to trace and cure the cause. For this, I've attached the hexadecimal laced dump below which may help and I've also saved copies of the crash log from the last 12 months and can email it to someone if it will help to get to the bottom of my problem. Btw, I've always kept my OS and virus protection up to date and there were never any "events" on my iMac that I know of.
I live these days off the beaten track in S. E. Asia well away from the possibility of visiting an Apple store so any helpful suggestions would be really great.
Thanks, Henry
Hardware Overview:
Machine Name: iMac G5
Machine Model: PowerMac8,1
CPU Type: PowerPC G5 (3.0)
Number Of CPUs: 1
CPU Speed: 1.8 GHz
L2 Cache (per CPU): 512 KB
Memory: 512 MB
Bus Speed: 600 MHz
Boot ROM Version: 5.2.2f2
Serial Number: *********
System Software Overview:
System Version: Mac OS X 10.4.9 (8P135)
Kernel Version: Darwin 8.9.0
Boot Volume: Macintosh HD
Computer Name: ********
User Name: ********
The most recent crash :
Tue Apr 24 09:44:01 2007
Unresolved kernel trap(cpu 0): 0x700 - Program DAR=0x00000000001BF670 PC=0x000000000D19BDFC
Latest crash info for cpu 0:
Exception state (sv=0x1D32CA00)
PC=0x0D19BDFC; MSR=0x00089030; DAR=0x001BF670; DSISR=0x40000000; LR=0x0D19BDFC; R1=0x0D19B970; XCP=0x0000001C (0x700 - Program)
Backtrace:
0x0D19BDFC
Proceeding back via exception chain:
Exception state (sv=0x1D32CA00)
previously dumped as "Latest" state. skipping...
Exception state (sv=0x1D336000)
PC=0x9000642C; MSR=0x0200F030; DAR=0x001BF670; DSISR=0x40000000; LR=0x92BBFE88; R1=0xBFFFCC80; XCP=0x00000030 (0xC00 - System call)
Kernel version:
Darwin Kernel Version 8.9.0: Thu Feb 22 20:54:07 PST 2007; root:xnu-792.17.14~1/RELEASE_PPC
panic(cpu 0 caller 0xFFFF0007): 0x700 - Program
Latest stack backtrace for cpu 0:
Backtrace:
0x000952D8 0x000957F0 0x00026898 0x000A8004 0x000AB980
Proceeding back via exception chain:
Exception state (sv=0x1D32CA00)
PC=0x0D19BDFC; MSR=0x00089030; DAR=0x001BF670; DSISR=0x40000000; LR=0x0D19BDFC; R1=0x0D19B970; XCP=0x0000001C (0x700 - Program)
Backtrace:
0x0D19BDFC
Exception state (sv=0x1D336000)
PC=0x9000642C; MSR=0x0200F030; DAR=0x001BF670; DSISR=0x40000000; LR=0x92BBFE88; R1=0xBFFFCC80; XCP=0x00000030 (0xC00 - System call)
Kernel version:
Darwin Kernel Version 8.9.0: Thu Feb 22 20:54:07 PST 2007; root:xnu-792.17.14~1/RELEASE_PPC
imac G5   Mac OS X (10.4.1)  

Answer 1

Hi Henry
Here are the standard four things I do when the Mac OS begin to go awry, apart from restarting, which you have already done:
Repair pemissions:
Launch Disk Utility (Apolications > Utilities > Disk Utlity) On the left side of the DU dailogue window select your hard drive, then click on the First Aid tab at top left of centre and click on "Repair Disk Permissions" button at the bottom left centre. It may go on for some time. I usually run the repair procedure a second time.
Repairing permissions is a good thing to do before and after installing software, as especially before and after an OS update.
Resetting PRAM
1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command (this may be the alt key if you have a non-mac keyboard)-Option-P-R keys. You must press this key combination before the gray screen appears.
5. Hold the keys down until the computer restarts three times.
6. Release the keys.
7. You will need to reset your computer clock after this procedure.
Resetting Open Firmware
1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, O, and F. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-O-F keys. You must press this key combination before the gray screen appears.
5. A grey screen with small black type will appear.
6. Type in: reset-nvram
7. Press Return key.
8. Type in: reset-all
9. Press Return key
10. Computer will restart
Single User mode
1. Shut down the computer.
2. Turn on the computer.
3. Press and hold the Command-S keys. You must press this key combination before the gray screen appears.
4. A long stream of white type on a black screen will appear.
5. When the streaming text stops type in: sbin/fsck -fy
making sure there is a space is between the k and the hyphen.
6. Press Return key.
8. More white type will appear. This can go on for some time especially if the computer has a problem.
When this stops the final text will either read "The volume Macintosh_HD (or whatever the HD is called) appears to be okay
or it will report that a fault has or has not been repaired.
9. Type in reboot
10. Computer will restart
Let us know how you get on.