Thanks, both. If either of you gets a chance to try the latest 2.6.32.y kernel from squeeze (it should work fine on a squeeze or wheezy/sid system), then that would be interesting.
I'm not sure what 2.6.32.y means. I've installed 2.6.32-5-686, which seems to be recent. That has the same problem (errors after loading ipmi modules), though.
Ian