Windows XP Domain Issue

I have a client with a laptop(used got a “deal” on it, meaning of course no XP or other software cd’s) running Windows XP Pro SP2. Went to join it to a windows 2003 domain but the network id is greyed out. If you click change the domain & workgroup boxes are greyed out. You can change the computer name but not the workgroup name or join it to a domain. This is one I have never seen before and have yet to turn up anything on Google or at Microsoft. Any ideas would be appreciated.
Pat