NT Login issue

NT4 box. I am domain admin. Get login error after I put my password in:

“The system could not log you on to this domain because the system’s computer account in it’s primary domain is missing or the password is incorrect”

Nothing wrong with mypassword. Tested it on other PC’s, with same domain. PC sees the ntwork (can ping stuff – while logged in as local administrator.
Anyone seen this before? Is the TCP/IP messed up?
The PC was an older one, and may have been added to another domain, in olden times…but this doesn’t make sense, as I re-installed the NIC, new IP’s, etc…

Any help appreciated…