I administer a small NT 3.51 SP5 domain that has been stable for literally
years. Client W/Ss were originally W95/98. Last year I replaced one with a
new W2K Pro computer. I was able to make the computer a member of the domain
and add the user's (non-Admin) domain account as a local
Administrators-group account. All was well.

I'm now replacing two more clients with XP Pro boxes. I can join the machine
to the domain ("Welcome to the ... domain") and the machine account is
present on the NT Server. However, any attempt to add a domain account as a
local account of any kind (standard, restricted or other/admin) results in a
"loss of trust" message:

The trust relationship between this workstation and the primary domain
failed.

I can fire up the Accounts control panel, Add User, go into Advanced, supply
the domain admin user name and password, it returns the list of domain
accounts, I choose one and hit "go". This process works fine on W2K Pro but
fails on these XP Pro boxes.

...and naturally I can't log in to the XP Pro box as the domain admin
because there isn't a local account there yet! Catch-22.

Any ideas on what the problem is/workarounds?