passwd does not work

I work with SuSE 6.2 kernel 2.2.10 on some linux-boxes Today I made a new user with "useradd <username>" (I was logged in as root via ssh), and tried at the next command, to give this new user a password with passwd <username>. The system replies: passwd: Unknown user <username> but the user is listed in /etc/passwd and /etc/shadow but it is not possible to set a new password with "passwd". I checked the passwd-binary with tripwire, but checksums are OK Trying with "userdel" to remove the user, causes system to tell: userdel: user <username> does not exist so I decided to remove the lines manually. Might it be that the system is compromised by intruders? Am I blind for some easy things? Thanks for all ideas! Thomas Hartl