I don't suppose anyone knows what might have cause this:

CPU 0: fatal kernel trap:

CPU 0    trap entry = 0x2 (memory management fault)
CPU 0    a0         = 0x0
CPU 0    a1         = 0x1
CPU 0    a2         = 0xffffffffffffffff
CPU 0    pc         = 0x0
CPU 0    ra         = 0x0
CPU 0    pv         = 0xe3af7
CPU 0    curproc    = 0xfffffc00076c08b8
CPU 0        pid = 20307, comm = sshd

panic: trap
Begin traceback...
alpha trace requires known PC =eject=
End traceback...
syncing disks... 2 2 2 done

Unfortunately, I wasn't able to get a crash dump (not enough disk
space in /var/crash, and after the system came back up, I tried
running savecore to put the dump elsewhere, and it said that there was
no core dump).

[ using 333656 bytes of netbsd ELF symbol table ]
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 1.6_RC1 (YERFABLE) #195: Tue Aug 20 06:27:38 CDT 2002
    khym@yerfable.azeotrope.org:/usr2/obj.alpha/YERFABLE
Digital AlphaPC 164 500 MHz, s/n
8192 byte page size, 1 processor.
total memory = 256 MB
(2472 KB reserved for PROM, 253 MB used by NetBSD)
avail memory = 231 MB
using 1635 buffers containing 13080 KB of memory
mainbus0 (root)
cpu0 at mainbus0: ID 0 (primary), 21164A-2
cpu0: Architecture extensions: 1<BWX>
cia0 at mainbus0: DECchip 2117x Core Logic Chipset (ALCOR/ALCOR2), pass 3
cia0: extended capabilities: 21<DWEN,BWEN>
cia0: using BWX for PCI config access
pci0 at cia0 bus 0
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
fxp0 at pci0 dev 5 function 0: Intel i82557 Ethernet, rev 1
fxp0: interrupting at eb164 irq 2
fxp0: Ethernet address 00:a0:c9:13:61:7e
nsphy0 at fxp0 phy 1: DP83840 10/100 media interface, rev. 0
nsphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
esiop0 at pci0 dev 6 function 0: Symbios Logic 53c875 (ultra-wide scsi)
esiop0: using on-board RAM
esiop0: interrupting at eb164 irq 0
scsibus0 at esiop0: 16 targets, 8 luns per target
pciide0 at pci0 dev 7 function 0: Promise Ultra100/ATA Bus Master IDE Accelerator (rev. 0x02)
pciide0: Changing IO from 0x8000 to 0x8000
pciide0: Changing IO from 0x8010 to 0x8010
pciide0: Changing IO from 0x0 to 0x8020
pciide0: Changing IO from 0x0 to 0x8030
pciide0: Changing IO from 0x8040 to 0x8040
pciide0: bus-master DMA support present
pciide0: primary channel configured to native-PCI mode
pciide0: using eb164 irq 1 for native-PCI interrupt
wd0 at pciide0 channel 0 drive 0: <MAXTOR 6L080J4>
wd0: drive supports 16-sector PIO transfers, LBA addressing
wd0: 76345 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 156355584 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 5 (Ultra/100) (using DMA data transfers)
pciide0: secondary channel configured to native-PCI mode
pciide0: secondary channel ignored (disabled)
sio0 at pci0 dev 8 function 0: Intel 82378ZB System I/O (SIO) (rev. 0x43)
vga0 at pci0 dev 9 function 0: Trident Microsystems TGUI 9660 (rev. 0xd3)
wsdisplay0 at vga0 kbdmux 1: console (80x25, vt100 emulation)
wsmux1: connecting to wsdisplay0
pciide1 at pci0 dev 11 function 0: CMD Technology PCI0646 (rev. 0x01)
pciide1: bus-master DMA support present
pciide1: primary channel wired to compatibility mode
atapibus0 at pciide1 channel 0: 2 targets
cd0 at atapibus0 drive 0: <ICD-3600AT, , A01> type 5 cdrom removable
cd0: 32-bit data port
cd0: drive supports PIO mode 3, DMA mode 2
pciide1: primary channel interrupting at isa irq 14
cd0(pciide1:0:0): using PIO mode 3, DMA mode 1 (using DMA data transfers)
pciide1: secondary channel wired to compatibility mode
pciide1: secondary channel ignored (disabled)
isa0 at sio0
com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
com1 at isa0 port 0x2f8-0x2ff irq 3: ns16550a, working fifo
pckbc0 at isa0 port 0x60-0x64
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
lpt0 at isa0 port 0x3bc-0x3bf irq 7
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
isabeep0 at pcppi0
isapnp0 at isa0 port 0x279: ISA Plug 'n Play device support
fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2
mcclock0 at isa0 port 0x70-0x71: mc146818 or compatible
isapnp0: read port 0x203
com2 at isapnp0 port 0x3e8/8 irq 5: ns16550a, working fifo
stray isa irq 5
scsibus0: waiting 2 seconds for devices to settle...
sd0 at scsibus0 target 0 lun 0: <Quantum, XP32150W, L915> SCSI2 0/direct fixed
sd0: 2151 MB, 3907 cyl, 10 head, 112 sec, 512 bytes/sect x 4406960 sectors
sd0: sync (100.0ns offset 15), 16-bit (20.000MB/s) transfers, tagged queueing
cd1 at scsibus0 target 4 lun 0: <PLEXTOR, CD-R   PX-R412C, 1.07> SCSI2 5/cdrom removable
cd1: sync (100.0ns offset 8), 8-bit (10.000MB/s) transfers
IPsec: Initialized Security Association Processing.
root on sd0a dumps on sd0b
root file system type: ffs
wsdisplay0: screen 1 added (80x25, vt100 emulation)
wsdisplay0: screen 2 added (80x25, vt100 emulation)
wsdisplay0: screen 3 added (80x25, vt100 emulation)
wsdisplay0: screen 4 added (80x25, vt100 emulation)

-- 
Name: Dave Huang         |  Mammal, mammal / their names are called /
INet: khym@azeotrope.org |  they raise a paw / the bat, the cat /
FurryMUCK: Dahan         |  dolphin and dog / koala bear and hog -- TMBG
Dahan: Hani G Y+C 26 Y++ L+++ W- C++ T++ A+ E+ S++ V++ F- Q+++ P+ B+ PA+ PL++