"unexpected status bit(s) 800000<PCIPERR>" and "PCI parity error" messages with twe and 3ware Escalade 7506-4LP

First, let me apologize if this message is poorly formatted.  I'm stuck with
using Outlook Express for the moment.  That said...

I just installed a 3ware Escalade 7506-4LP with a pair of Western Digital
120GB as a RAID 1.  I booted from a 5.2-R CD, the controller was found, but
seems to have a problem:

twe0: <3ware 7000 series Storage Controller. Driver version 1.50.00.000>
port 0xb800-0xb80f mem 0xe0000000-0xe07fffff,0xe0800000-0xe080000f irq 5 at
device 9.0 on pci0
twe0: PCI parity error: Reseat card, move card or buggy device present.twe0:
4 ports, Firmware FE7X 1.05.00.065, BIOS BE7X 1.08.00.048

The probe continues, down to where the disks are found and created:

twed0: <Unit 0, TwinStor, Normal> on twe0
twed0: 114472MB (234439600 sectors)
GEOM: create disk twed0 dp=0xc459b40c
twe0: unexpected status bit(s) 800000<PCIPERR>
twe0: PCI parity error: Reseat card, move card or buggy device present.

The second message repeats 20 or so times, then I get the first again, then
another two dozen or so of the second, etc., at a rate of several per
second.  Taking a hint from the error message, I safely powered down the
system, pulled the card, checked for rogue dust-bunnies, put it back in the
same slot and rebooted.  No more error messages.  Not trusting this
entirely, I reboot, got the messages again.  I powered down, pulled the
card, put it back in the same slot, reboot, no change.  Powered down again,
moved the card to a different slot, no messages.  Powered down again,
rebooted, got the messages again.  Figuring I couldn't possibly be the first
person to run into this problem, I searched the mailing lists and googled
for answers.  No luck.  There wasn't anything mentioned in the Errata that
came with the controller, either.

Is this a known issue?  What is going on here?  Can this be fixed?  Is the
card/drive (or card/drive combination) hosed?  Is this related to the
incompatibility between Western Digital "JB series" drives and 3ware
controllers I see alluded to in various places?

Some further details about the system:

The card is 32-bit, 33Mhz slot.  I don't have any 64-bit slots.  I already
checked the clearance and the 64-bit tab isn't touching anything.  Card's
version numbers from hitting Shift-F5 in the:

BIOS: BE7X 1.08.00.048
Firmware: FE7X 1.05.00.065
Monitor: ME7X 1.01.00.038

The two drives in the RAID 1 are both Western Digital WD1200JB-00EVA00.  The
system I'm building this on is a Pentium 3 with a 440BX chipset.