passwords not recognized when su'ing from a terminal

[Alain Cochard]

Mikkel L. Ellertson writes:

 > >  > Alain Cochard wrote on Fri, Jul 20 2007 at 11:59 (+0200):
 > > 
 > >  > > Just a few days ago, I stopped being able to 'su' or 'su
 > >  > > some_user' from a terminal: the passwords are no longer accepted.
 > >  > > Same problem to unlock a session (need to enter the password).

 > A long shot, but check your  /etc/sudoers file.

I don't know how to do that.  Besides, neither the file not its status
have changed since the distribution installation...

Thanks,
Alain