(This post was originally meant to be a rant and a request for help, but
while writing the final paragraph i found the solution. It's still a
rant, but i figured i'd post my solution here in case someone else runs
into the same issue.)
I've just spent several hours banging my head against a broken cluster
node. My system is a 32-bit SLES 10 VM running on VMware ESX 3.5.x.
I upgraded from SLES10 SP3 and OES2 SP2 to the next service packs for
each (using the move-to-oes-sp3 script in yast2 online_update).
Everything went well for the first few update/reboot sequences, then
after the final reboot on SLES10 SP4