check the permissions on su(1). they should be:
% ls -l /usr/bin/su
-r-sr-xr-x 1 root bin 16384 Jun 15 19:15 /usr/bin/su
perhaps the suid bit was removed by accident?
if so, as root
# chmod u+s /usr/bin/su
should fix it.
: Suddenly I'm having a problem using "su" from my regular user account,
: which is part of the "wheel" group. It worked for a while, but now
: after giving the correct password I just get "Sorry" back. (There's
: no problem logging directly into the root account.) I'm new to OpenBSD
: and am still learning the various mystical incantations used to maintain
: the system -- what is likely causing this problem?
: Roger Blake
: (remove second "g" and second "m" from address for email)