This is a long shot, but...
I had a similar problem on machines with hardware locked R.14 installed
previously, when I switched to the ADLM for 2000.
This may not be the solution, but has the machine ever had the Rainbow
Technologies, net sentinel drivers installed?
I had the EXACT same symptoms on machines in my office.
AutoCAD R.14 Uninstall did not solve the problem. Neither did removing ALL
references to AutoCAD in the registry! Nothing worked!
Seems as though the AutoCAD uninstall failed to remove the Sentinel
Hardware Lock application.
I spent months trying to figure out why this was happening to me...
Thought that I was loosing my mind!
Finally I sent all of the installation disks to AutoDesk and they were kind
enough to duplicate the problem, and were able to find the solution.
Do a Find the rainbow sentinel application, like:
sent*.*
I think that it was called sentwin95.exe or sent95.exe or something like
that. (I dont have it anymore, so I cant tell you)
If it is on the machine, there is an uninstall within the application.
I dont envy you on this one...
I probably spent more than 40 hours trying to figure it out. Until
Autodesk gave me the solution, the only fix I could find at the time was to
totally low-level format the hard disk, and re-install the OS from the
ground up!
(I was convinced that AutoDesk had put some kind of non-removable Hook on
the Hard Disk that no one knew about, or would disclose, to catch pirates
who had at one time installed AutoCAD!, I swear, I was loosin it)
K.