This is typically a network connectivity issue. Log in as a local admin to the machine. Check and see if you can ping your router. If you can, unjoin and rejoin the machine to the domain. If you cannot ping your router check the port to which the computer is connected on the switch. Get assistance from the network engineers if you are unable to do this yourself.
But first find out why it is happened !
Error may appear if a system is replaced without change the name or use the same computer name, but not deleting the duplicate computer name from the Active Directory domain. Another cause is related to security identifier, i.e. sid issue. One more cause is that account for the workstation was accidentally deleted from the Active Directory domain.
To overcome this issue….
1. Login to the Windows Server 2003 and run dsa.msc > and delete the computer account from the domain
2.Login to the Windows XP with administrator rights.
NOTE: If u not to login, try to disconnect the network cable and login by using a domain administrator user that was used to login on the XP before.
3. Control Panel > System > Computer Name tab.
4.Click Change, to remove computer from the domain
NOTE: Select domain. By caution, write domain name in text box. Select the Workgroup to remove the computer from there, & supply a workgroup name. Now OK and reboot
5. After restart, Control Panel > System > Computer Name tab > Change
6. Now again rejoin the domain
CAUTION: It may ask to enter the details one of the Domain Admin users
7. Click OK and reboot the computer.