NCR 53c875 assertion failure

[Barclay Osborn <bosborn@cyberpass.net>]

Has anyone seen this before?:

I was working on a machine behind my gateway, when packets stopped going
through, so I checked the console on the gateway - this message was
slamming the screen:
sd1 (ncr00:6:0): COMMAND FAILED (4 28) @ 0xf08fc800 assertion "cp" failed:
file "/usr/src/sys/dev/pci/ncr.c", line 6550
(the function is ncr_int_sir( ncb_p np ), the default case of the first
switch when it's looking up the ccb - although I hvae no idea what that
means, that's what the comment says)

When I tried to shutdown, the system couldn't sync sd1 (sd0, which is my
root disk, was fine), and the unmount of all filesystems on sd1 failed with
error 5.

Upon reboot, dmesg spat out a fatal error on ncr "(flush fifos)", and
forced a soft reboot.  Upon this second reboot, I got:
dkcsum: sd1 had no matching BIOS disk.
(sd0 had the normal message)
rootdev=0x400 rrootdev=0xd00 rawdev=0xd02
panic: cannot open disk, 0x400/0xd00, error 5.

I couldn't crash boot, since the dump area was on sd1, and so just shutdown
and cold booted.  The machine seems to be working fine right now.

Any help would be appreciated,
Barclay

(the specs)
HP Kayak XA, PII 266, NCR 53c875 UW SCSI adapter, OpenBSD 2.5 w/ a pared
down kernel & ipfiltering, but otherwise reasonably generic.  The system
was just recently upgraded to 2.5 (about a week ago) and was fine up until
today, and had been running 2.3 with no problems for over a year prior to
the upgrade.

Portions of a "normal" dmesg:
ncr0 at pci2 dev 0 function 0 "Symbios Logic 53c875" rev 0x04: ncr 53c875
fast20 wide scsi, irq 9
scsibus0 at ncr0: 16 targets
sd0 at scsibus0 targ 0 lun 0: <QUANTUM, VIKING 2.3 WSE, 8808> SCSI2
0/direct fixed
sd0: sd0(ncr0:0:0): WIDE SCSI (16 bit) enabled
sd0(ncr0:0:0): 40.0 MB/s (50 ns, offset 16)
2171MB, 6144 cyl, 4 head, 180 sec, 512 bytes/sec, 4446801 sec total
sd1 at scsibus0 targ 6 lun 0: <IBM, DDRS-34560W, S92A> SCSI2 0/direct fixed
sd1: sd1(ncr0:6:0): WIDE SCSI (16 bit) enabled
sd1(ncr0:6:0): 40.0 MB/s (50 ns, offset 15)
4357MB, 8387 cyl, 5 head, 212 sec, 512 bytes/sec, 8925000 sec total

----  Barclay Osborn                                                   ----
---   bosborn@cyberpass.net                     barclay@simplemail.net  ---
--                                                                       --
---              Mister Order, he runs at a very good pace              ---
----             But old Mother Chaos is winning the race              ----
----- Lord Omar Khayyam Ravenhurst, K.S.C., The Honest Book of Truth  -----