user accounts messed up

[Jona Joachim]

Hi!
I did something quite stupid...
I installed postgresql from ports and created an unprivileged user
account for it. I wanted to install the database in /var/pgsql and
wanted to chown the folder to the unprivileged user.
To do this, I entered the following as root: chown -R /var/pgsql/
As this command took more than two seconds I presumed chown had
followed .. and so I hit Ctrl-C. After having done this I tried to
switch to the unprivileged user account with su and it said something
like "setuid not running". After having tried to recover from this
situation without success I decided to reboot the system. Now I can't
login to any user account anymore, not even root. I am told the
password is not correct. I tried to boot in single user mode, mount
/usr and change the root password with passwd but I am denied
permission to change master.passwd. Is it possible that the user
database is corrupt? I would be glad if anyone was able to help me.
Greetings, Jona