Authentication Failed - message when trying to login

["Dr. Jones" <drjones vii com>]

I can't log on to my Pentium II machine which is running debian 3.0. Two
kernels are installed, with 2.4.18 and 2.4.20.

Until a few days ago, I was able to boot up and run with 2.4.20. After my
system froze and required a cold boot, plus a painfully long run of fsck
/dev/hda1 to get it revived, now it gets to the Gnome Desktop Manager login
screen, and refuses to move forward.

When I type in my user name, or root, gdm responds with "Authentication
Failed" and does not present the password prompt. To get out of this I hit
ctrl-alt-f2, then ctrl-alt-del.

Last night I was rebooting, and while at the GRUB menu, I selected the
2.4.18 kernel to see if it would boot differently. It booted up the same,
rendering the same results at the gdm dialogue, however, if I booted in
maintenance mode, after entering my root password, which it accepts, I was
able to log on, to run apt-get update from the console.

When attempting this under 2.4.20, I could not even get an IP address, the
tulip NIC driver would not load and give me 'net access.

I believe I have a PAM problem, as all my directories appear intact, in
/home and elsewhere.

What can I do to resolve this, to get net access under 2.4.20 so that I can
get my linux box working as normal?

Thanks for any help,

Scott