Can't change the way you logon!

Hello,
This problem is with my uncle's computer. He has the classic logon when he wants the normal XP welcome screen. When I go to the control panel, click on user accounts, and click Change the way users logon, it says "Client Services for NetWare has disabled the welcome screen and fast user switching. To restore these features, you must uninstall client services for NetWare."

Please tell me how to uninstall or what to do.
Thanks.

http://support.microsoft.com/?kbid=315347