Remote Desktop to Windows 2003 Server SP2 error Domain Controller is Unavailable

A Windows Server 2003 SP2 server prevents a workstation from connecting via Remote Desktop unless the server can contact the domain-- even if the server has cached credentials available for the domain account the client is trying to use.  This domain-disconnected case is probably common a scenario, where workstation occasionally connects to the domain but generally log in via cached credentials.

The error you'll get in the Remote Desktop client is this:
    The system cannot log you on due to the following error:
    The specified domain either does not exist or cannot be contacted

The easiest fix to go to Microsoft site and download HotFix KB902336. Or you may try to fix it manually by connect to Registry Editor remotely.

1. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server
2. Click Edit, point to New, and then click DWORD Value.
3. In the New Value #1 box, type IgnoreRegUserConfigErrors, and then press ENTER.
4. Right-click IgnoreRegUserConfigErrors, and then click Modify.
5. In the Value data box, type 1, click Decimal, and then click OK.
6. Quit Registry Editor.