Posting this solution for posterity:
To solve the above problem, do the following:
1) Edit the /etc/modules file and add the following line:
2) Edit the /etc/rc0.d/S90halt file and remark out the following lines:
# if grep -qs '^md.*active' /proc/mdstat
and remark out...
# if [ "$NETDOWN" = "no" ]; then
3) Add the following args to the kernel line in /boot/grub/menu.lst
noacpi acpi=off pci=nopci
You may be able to omit the pci=nopci
argument as I am not convinced that it is related to the problem. But the bug is solved for me so I am not going to prove or disprove that argument just yet.