Run the Group Policy snap-in (gpedit.msc). Under Local Computer Policy > Computer Configuration > Windows Settings > Security Settings > Security Options set “Network access: Sharing and security model for local accounts” to “Classic on the Windows Server 2003 family and Windows XP.”

Run gpupdate. This program is described here:

http://www.microsoft.com/resources/documentation/windows/xp/
    all/proddocs/en-us/refrgp.mspx?mfr=true