Windows Login Test tools

[Stephen Seal]

Hi everyone:

I'm hoping that someone on these lists can help.  

I've been trying to find a test tool for Win95/98/NT that can help 
diagnose problems with NT Domain login and authentication.  I'm hoping 
that someone in the Samba community has a tool or knows where to find 
a REALLY GOOD description/overview of the NT Domain login process.

Here's my problem scenario:  If a user (a non technical user I might 
add) remotely connects to a network, and submits their 
username/password to a PDC, they sometimes get the "very helpful" 
Windows message "Cannot log in to the Domain" (or similar nonsense).  
What can be done at this point to help diagnose this problem? There 
appears to be no Windows tool to help resolve WHY they can't log in.

Can anyone help?

Frustratinly yours,
Steve