Try to first login as 'root' from the console. If successful, then
unlock the account, run:
# /usr/lbin/modprpw -k root
If you can't then you will need to boot into single-user mode.
Interrupt the boot sequence and from the ISL prompt:
ISL> hpux -is
Wait for the prompt and change the passwd and unlock the account.
If you use 'sudo' you can get around this this problem.
Invest some time and install it. Here is the link:
http://hpux.connect.org.uk/hppd/hpux/Sysadmin/sudo-1.6.6/
Anyone for a Mutiny ?