Why Multiple Kernel "issues" w/G4 iMac/Tiger?

Question

Folks:
Lately have had a run of KPs in my ten year old +- G4 iMac . . . so we know it's "old" but overall when it's running well, it's fine.  I ran the Apple Hardware test and that shows "OK" . . . I have SmartReporter and that shows fine.  I booted up in ext HD and ran DU to Repair Disk, and I ran Onyx as well . . . .  Today, I was trying to see if it was related to the browser, lately Ten4Fox, so I switched back to Camino but got the same "we don't support your browser" and KP there as well . . . .  Then I tried to not use the internet at all and things were going well for awhile, but then got another KP that way.  The computer has stopped generating "Crash Reports" to send to Apple and now just gives the kernel panic in a CLI note in black bars with white text that drops down over the desktop; multiple times the "grey" screen with the "You need to restart" happened, we aren't wasting time doing that now . . . the mouse and screen freezes and the CLI kernel trap info shows up.  BTW, I also had done a PRAM reset, and then I saw BDAqua's post here about doing it three times, which I did the other day and it seemed like the problem was fixed . . . until today with 3 of them.  Seems like it can happen right on revive from sleep or after running the computer for awhile.  Any thoughts?  I've been told already, "It's time for a new computer" and I'm reconciled to that in the near-long term as the "answer" . . . just wondering if I can get some insight into troubleshooting my dear old G4 friend and keep it going for awhile longer???  Can anybody hep me?  Final note, I've got the int HD partitioned and running Xu/Lu 12.0.4, the crash problem started there and that's not new, but then continued over into the OSX side.  Today, I was logged into Xu/Lu and did not have any KP while there . . . but did again back in OSX . . . .  Is it "soft" or "hard" ware issue?  I can't tell . . . .  Many thanks for any insights.
e.e.p.

Answer 1

BDAqua:
Ah, "thermal paste" . . . Austin Powers didn't think about that one . . . possibly there is a flaw in the thermal paste . . . .   BTW, I did get some expert feedback on one of my earlier crash reports and the different RAM types was pointed out as a possible source of problems . . . and indeed it might be, but that difference has been there since the very first day . . . ten + years ago???  Would that suddenly become a problem?  The previous reports didn't seem to offer much in terms of clues . . . this is the first time I saw "uncorrectable machine check" . . . that sounds more serious . . . even ominous . . . maybe this is all due to the impending Halloween?????  Hmmmmmmmm . . . .
e.e.p.
panic(cpu 0 caller 0x000A8C00): Uncorrectable machine check: pc = 00000000000A3650, msr = 0000000000141000, dsisr = 40000000, dar = 00000000000BD000
  AsyncSrc = 0000000000000000, CoreFIR = 0000000000000000
     L2FIR = 0000000000000000,  BusFir = 0000000000000000
Latest stack backtrace for cpu 0:
      Backtrace:
         0x000954F8 0x00095A10 0x00026898 0x000A8C00 0x000A7E90 0x000ABB80
Proceeding back via exception chain:
   Exception state (sv=0x2D62E500)
      PC=0x000A3650; MSR=0x00141000; DAR=0x000BD000; DSISR=0x40000000; LR=0x0009D0EC; R1=0x0CED3C50; XCP=0x00000008 (0x200 - Machine check)
      Backtrace:
0x00000000 0x0009A1FC 0x00098F78 0x00062AC8 0x000A865C 0x000ABB80
   Exception state (sv=0x2D5EC500)
      PC=0xFFFF8A50; MSR=0x0200D030; DAR=0x000BD000; DSISR=0x40000000; LR=0x00024638; R1=0xBFFF6FD0; XCP=0x0000000C (0x300 - Data access)
Kernel version:
Darwin Kernel Version 8.11.0: Wed Oct 10 18:26:00 PDT 2007; root:xnu-792.24.17~1/RELEASE_PPCModel: PowerMac4,2, BootROM 4.3.4f2, 1 processors, PowerPC G4  (2.1), 800 MHz, 512 MB
Graphics: NVIDIA GeForce2 MX, GeForce2 MX, AGP, 32 MB
Memory Module: DIMM0/J12, 256 MB, SDRAM, PC100-322S
Memory Module: DIMM1/J13, 256 MB, SDRAM, PC133-333
AirPort: AirPort, 9.52
Modem: Dash2, UCJ, V.92, 1.0F, APPLE VERSION 2.6.6
Network Service: Built-in Ethernet, Ethernet, en0
Parallel ATA Device: ST360020A, 55.9 GB
Parallel ATA Device: PIONEER DVD-RW  DVR-104
USB Device: Keyboard Hub, Apple, Inc., Up to 12 Mb/sec, 500 mA
USB Device: USB/PS2 Wheel Mouse, Kensington, Up to 1.5 Mb/sec, 100 mA
USB Device: Apple Keyboard, Apple, Inc, Up to 1.5 Mb/sec, 220 mA
Model: PowerMac4,2, BootROM 4.3.4f2, 1 processors, PowerPC G4  (2.1), 800 MHz, 512 MB
Graphics: NVIDIA GeForce2 MX, GeForce2 MX, AGP, 32 MB
Memory Module: DIMM0/J12, 256 MB, SDRAM, PC100-322S
Memory Module: DIMM1/J13, 256 MB, SDRAM, PC133-333
AirPort: AirPort, 9.52
Modem: Dash2, UCJ, V.92, 1.0F, APPLE VERSION 2.6.6
Network Service: Built-in Ethernet, Ethernet, en0
Parallel ATA Device: ST360020A, 55.9 GB
Parallel ATA Device: PIONEER DVD-RW  DVR-104
USB Device: Keyboard Hub, Apple, Inc., Up to 12 Mb/sec, 500 mA
USB Device: USB/PS2 Wheel Mouse, Kensington, Up to 1.5 Mb/sec, 100 mA
USB Device: Apple Keyboard, Apple, Inc, Up to 1.5 Mb/sec, 220 mA