I'm applying sp5 to a number of servers in order to prepare them for a
migration to nw 6.5 sp5 but I'm being stopped by the fact that after
applying sp5 to a group of servers they hang on reboot, never in the same

I've checked everything I can think of that might be causing the problem
hyperthreading, disk drivers, but nothing resolves the issue. Backreving
the support pack takes me back to a stable server but prevents me from
upgradeing to nw 6.5, I don't want to have to kill the server and start
from fresh as there are lots of servers seeing this issue.