Trust Relation

A users computer, connected to our domain started denying access to the network. It states that there is no trust relationship. He can login to the local machine and I see it active in server manager but he cannot login to our domain. I, as the domain administrator cannot login to the domain on his machine so I know its not a user login problem. His computer is a work station added to the domain and is running W2K.Thats for any assistance you might render.