Sudden Kernel Panicking: MacBook 3,1; 4Gb; 10.5.4

Question

Hi!
My Macbook suddenly started kernel panicking this afternoon. It's been very stable until this point. I'm primarily wondering what steps I ought to perform before contacting Apple, as I'm still within my 1-year warranty.
I've run a brief AHT run (with no results) and am letting the it loop over night. I'd not had any SMART indication on the hard drive or anything, though I have not tried to run disk utility yet.
The extra RAM I installed was installed in November or December when I first bought the machine. I did unplug my USB mouse and FireWire hard drive to make sure they were not related, though I've been using them consistently. I've not installed any new software recently that I can recall; the most recent (I think) was the 10.5.4 update, and some of the iPhone-related updates--although not iTunes 7.7. (I don't remember what exactly.) I'd used the machine all day without problems, until the panics started after I returned from a meeting.
The panic seems to be occurring after login, anywhere from 1 to 30 minutes, in my experience. At first I thought it was Safari, but that was not borne out in later testing.
Several of the kernel panic logs (at least in the automatic reporting tool) appeared garbled; one un-garbled one that I got off of the machine is as follows:
Mon Jul 14 19:35:57 2008
Machine-check capabilities (cpu 0) 0x0000000000000806:
family: 6 model: 15 stepping: 11 microcode revision 179
Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz
6 error-reporting banks
threshold-based error status present
Machine-check status 0x0000000000000005
restart IP valid
machine-check in progress
MCA error-reporting registers:
IA32MC0STATUS(0x401): 0x1000000000000000 invalid
IA32MC1STATUS(0x405): 0x0000000000000000 invalid
IA32MC2STATUS(0x409): 0x0000000000000000 invalid
IA32MC3STATUS(0x40d): 0x0020000000000000 invalid
IA32MC4STATUS(0x411): 0x0000000000000011 invalid
IA32MC5STATUS(0x415): 0xb200001806000e0f valid
MCA error code : 0x0e0f
Model specific error code: 0x0600
Other information : 0x00000018
Threshold-based status : Undefined
Status bits:
Processor context corrupt
Error enabled
Uncorrected error
panic(cpu 0 caller 0x001A8656): Machine Check at 0x00420199, thread:0x76cd410, trapno:0x12, err:0x0, registers:
CR0: 0x8001003b, CR2: 0x55224000, CR3: 0x010e7000, CR4: 0x00000660
EAX: 0x068f0840, EBX: 0x0693eb00, ECX: 0x00000000, EDX: 0x00ca2680
ESP: 0x54f43568, EBP: 0x54f43568, ESI: 0x00000000, EDI: 0x07e5e280
EFL: 0x00000216, EIP: 0x00420199
Backtrace, Format - Frame : Return Address (4 potential args on stack)
0x4ece28 : 0x12b0fa (0x4592a4 0x4ece5c 0x133243 0x0)
0x4ece78 : 0x1a8656 (0x462504 0x420199 0x76cd410 0x12)
0x4ecf58 : 0x19fd93 (0x4ecf70 0x0 0x0 0x0)
0x54f43568 : 0xcfe88f (0x6940840 0x1 0x2 0x0)
0x54f43588 : 0xd01f9a (0x693eb00 0x0 0x100 0x0)
0x54f435e8 : 0x7dc405 (0x6852100 0x7e5e280 0x2bf548 0x0)
0x54f43658 : 0x7de619 (0x69ce000 0x7e5e280 0x2bf548 0x0)
0x54f436b8 : 0x7e1455 (0x69cbc00 0x57ea9000 0x0 0x7e5e280)
0x54f43718 : 0x7e78de (0x69cbc00 0x57ea9000 0x0 0x7e5e280)
0x54f437d8 : 0x2033bd (0x56b30820 0x1 0x0 0x0)
0x54f43828 : 0x1c8e87 (0x54f43918 0x1 0x1ca6d7c 0x119d809)
0x54f438d8 : 0x329b11 (0x69dff40 0x54f43918 0x54f43928 0x1c763a)
0x54f438f8 : 0x1f48dd (0x54f43918 0x0 0x1 0x7660184)
0x54f43928 : 0x1cd88d (0x56b30820 0x6cf6380 0x0 0x1000)
0x54f43a08 : 0x1cf3b0 (0x0 0x0 0xfffff1c0 0x5)
0x54f43b58 : 0x1d0a40 (0x1c0 0x0 0x0 0x0)
Backtrace continues...
Kernel loadable modules in backtrace (with dependencies):
com.apple.iokit.IOAHCIBlockStorage(1.1.0)@0xcfc000->0xd0bfff
dependency: com.apple.iokit.IOAHCIFamily(1.0.4)@0xc9d000
dependency: com.apple.iokit.IOStorageFamily(1.5.2)@0x7d9000
com.apple.iokit.IOStorageFamily(1.5.2)@0x7d9000->0x7f0fff
BSD process name corresponding to current thread: Dock
Mac OS version:
9E17
Kernel version:
Darwin Kernel Version 9.4.0: Mon Jun 9 19:30:53 PDT 2008; root:xnu-1228.5.20~1/RELEASE_I386
System model name: MacBook3,1 (Mac-F22788C8)

Answer 1

Well, the Disk Utility check didn't help--it froze again soon afterwards. However, my next step was to fun fsck from single-user mode. That didn't help either. But, I then did a SMC reset before booting again--by unplugging the AC adapter and the battery--and it seems that the computer is stable now. I had it on all night without problems. Hopefully, it will run throughout today, and I can consider it stable.
Is there anything in the kernel panic log that might be a pointer to a issue with the SMC?