I have noticed that we are having difficulties diagnosing network problems. Some Suggestions..

Check Cabling, and check for a light on the Hub.

Not being able to log on NT, this is often caused by incorrect workstation settings.

Try logging on as another workstation number.If this works go into Start-Programs- Administrative Tools-User Manager. Then delete the original workstation number.
Highlight the current workstation number, hit F8 to copy it to a new user.
Name the new user the original workstation number.

Problems with Nt logging onto Novell.

Click My Computer-Control Panel-CSNW.
Make sure Prefered Server name is correct.
Also make sure Run Login Script is checked.
Check to make sure that they are using only NT SP 4 or SP 5