I've tried the stable -k8 kernel. I've now also tried
linux-image-2.6.12-1-amd64-k8 from unstable.
In both cases it's causing the machine to reboot whilst trying to sync a
RAID5 array across 6 disks on two SATA controllers.
For information, I can build the array across the first 5 disks, and put
the FS on it and mount it. It's only when trying to add the parity disk,
and sync the array that the problem occurs. It's happened at different
stages of the sync - I've got as far as sync 40%, although it mostly
dies in the first few mins.