First of all, thx a lot to both of you for replying so promptly
[DMR] Here is more detail about my system
CPU: PIII i686 1GHz
NIC: Netgear something (it works perfectly fine, i can http, ssh, etc.)
Distro/Linux: Redhat 7.1 / 2.4.9-12
Static IP: 192.168.0.181
[wushu3d] I also have recently change the name of my host from the initial 'localhost.localdomain' to something more original, which i would not mind keeping :-)
Could my problem be related to pam.d or ipchains? My intuition is that the fact that the network/eth0 is enabled results in a change in the way password check is operated. There must be a configuration file somewhere, which i am not aware of, to indicate that password check remains local to the host...