[CentOS] An odd IPMI problem

Well, we're figure the board's got problems, but I installed OpenIPMI a
couple weeks ago, and fired it up as a service, then added a cron job.
That all ran well until last evening; we came in to find 5 zillion emails
complaining
Unable to open SDR for reading

I worked my way through logs, and googling, and then trying to run
ipmitool by hand, and it complains there's no such device as
/dev/ipmi[three versions].

More googling, and down to modprobe, then insmod, of ipmi_si. Then trying
to give it parameters, and it continually comes back (after 5 min of
trying) with "No such device".

One thing I note: after I found the docs for IPMI, I found the list of
parms <http://www.mjmwired.net/kernel/Documentation/IPMI.txt>, and gave
it, among other things, the slave_attrs. Then I look at dmesg and
/var/log/messages... and it seems to be utterly ignoring that parm. That
is, I say (and get)
$ insmod
/lib/modules/2.6.18-164.11.1.el5/kernel/drivers/char/ipmi/ipmi_si.ko
ports=0xca2 slave_addrs=0x10
insmod: error inserting
'/lib/modules/2.6.18-164.11.1.el5/kernel/drivers/char/ipmi/ipmi_si.ko': -1
No such device

and in the log
Mar 10 11:24:36 south kernel: IPMI System Interface driver.
Mar 10 11:24:36 south kernel: ipmi_si: Trying hardcoded-specified kcs
state machine at i/o address 0xca2, slave address 0x0, irq 0
Mar 10 11:26:28 south kernel: ipmi_si: There appears to be no BMC at this
location
Mar 10 11:26:28 south kernel: ipmi_si: Trying SMBIOS-specified kcs state
machine at i/o address 0xca2, slave address 0x20, irq 0
Mar 10 11:28:20 south kernel: ipmi_si: There appears to be no BMC at this
location
Mar 10 11:30:12 south kernel: ipmi_si: Unable to find any System Interface(s)

Notice that it's looking at slave_addrs of 0x0 and 0x20, *not* 0x10.

Any clues?

         mark