Windows XP Pro Domain Login Fails (erratic behavior)

Hello all,

Over the last two weeks the windows machines at our department (around
10) are not allowing the users to login to the domain. The computers
are loan computers that my department provides to faculty when they are
teaching a face to face class.
The computers are loaded with Windows XP Pro running latest updates
from Microsoft.

All domain users are of type Guests and their profiles get erased after
they log off. That keeps the amount of profiles to the minimum. There
is a local account which works when one tries to log in. However all
domain users when entering their credentials (after the CTRL+ALT+DEL
screen) and clicking OK, they get taken back to the CTRL+ALT+DEL screen
again. No error message is displayed and we are certain that the typed
info is correct. Of course the computers are plugged into the network.
The only solution was to reinstall Windows.

What could be causing this problem? How would I go about finding more
info from the computer logs?

Thanks

.