HELP! Users can't log

[Dipl agr Veronique Eyraud]

I can log on the machine as root, butanybody else gets thrown away.
No explanation in the console or SYSLOG.
I have checked
	the password file (yp used successfuly on another machine)
	the login directories are there and accessible
	the /etc/cshrc, .cshrc and .login (we are running the csh)

Everything looks desperately normal
Any idea? (My local support says I should reload the system  ---GASP!!!)