Slow Logon

Unit is running xp professional service pack 2. Logon times normal when booting up offline, or on our offices LAN connection. When booting up on a dock (same lan connection) bootup initially slow, as in 20-30 minutes. Gets progressively faster, but returns to slow state if user takes home or switches to direct lan connection, at which point logon time at the docking station returns to 20-30 minutes time frame. Appears to “hang” during the applying personal settings portion, though eventually goes. Suggestions?