The sequence to get a work around (whilst waiting for a response from Ubuntu) was:
- Try and strip out the I2O subsytem from the initrd created by initramfs and then find it fails to load the dpt_i2o driver at all.
- Use mkinitrd not mkinitramfs as that has enough sense not to include the I2O subsystem.
- Find that the machine then crashes after your disks are mounted because hotplug tries to load I2O when it begins during the init scripts.
- Remove or move somewhere innocuous the /lib/modules/2.6.12-9-686-smp/kernel/drivers/message/i2o directory and reboot.
- Update the bug report in the hope you won’t have to go through it again!
Finally my machine boots…