HP always told us @ and # could not used in password on HP-UX.
If somebody used them, then you should change password in single user mode.
But I have tried. It can be done by this step.
eg: Somebody's password is abc@123 or abc#123.
You can input password by:
abc\@123
or
abc\#123
Then you login into your system!
:)
Wish you enjoy it.
Ryan Gu