If a user has a special character in their password and they can log into Windows but when they attempt to log into an HPUX machine with SSH or Telnet they get a failed/incorrect password error message.
This warning can be found in the passwd man page:
Avoid password characters which have special meaning to the tty driver, such as # (erase) and @ (kill). You may not be able to login with these characters.
The special character in their password is sending kill/end signal to the tty driver.
To make sure the tty driver does not interpret the special character as a kill/end signal place a backward slash ( \ ) before the special character.
If your password is '$pecia!' you would then enter it as '\$pecia\!'