Its just authentication between domain controllers, try this to fix it, though a bit long winded. Please remember to back up the keys you change and make a note of the settings you change.
1. On the domain controller, click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters
3. In the right pane, double-click enablesecuritysignature, type 1 in the Value data box, and then click OK.
4. Double-click requiresecuritysignature, type 1 in the Value data box, and then click OK.
5. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanworkstation\parameters
6. In the right pane, double-click enablesecuritysignature, type 1 in the Value data box, and then click OK.
7. Double-click requiresecuritysignature, type 0 in the Value data box, and then click OK.
8. After you change these registry values, restart the Server and Workstation services. Do not restart the domain controller, because this action may cause Group Policy to change the registry values back to the earlier values.
9. Open the domain controller’s Sysvol share. To do this, click Start, click Run, type \\Server_Name\Sysvol, and then press ENTER. If the Sysvol share does not open, repeat steps 1 through 8.
10. Repeat steps 1 through 9 on each affected domain controller to make sure that each domain controller can access its own Sysvol share.
11. After you connect to the Sysvol share on each domain controller, open the Domain Controller Security Policy snap-in, and then configure the SMB signing policy settings. To do this, follow these steps:
a. Click Start, point to Programs, point to Administrative Tools, and then click Domain Controller Security Policy.
b. In the left pane, expand Local Policies, and then click Security Options.
c. In the right pane, double-click Microsoft network server: Digitally sign communications (always).
Note: In Windows 2000 Server, the equivalent policy setting is Digitally sign server communication (always).
Important: If you have client computers on the network that do not support SMB signing, you must not enable the Microsoft network server: Digitally sign communications (always) policy setting. If you enable this setting, you require SMB signing for all client communication, and client computers that do not support SMB signing will not be able to connect to other computers. For example, clients that are running Apple Macintosh OS X or Microsoft Windows 95 do not support SMB signing. If your network includes clients that do not support SMB signing, set this policy to disabled.
d. Click to select the Define this policy setting check box, click Enabled, and then click OK.
e. Double-click Microsoft network server: Digitally sign communications (if client agrees).
Note: For Windows 2000 Server, the equivalent policy setting is Digitally sign server communication (when possible).
f. Click to select the Define this policy setting check box, and then click Enabled.
g. Click OK.
h. Double-click Microsoft network client: Digitally sign communications (always).
i. Click to clear the Define this policy setting check box, and then click OK.
j. Double-click Microsoft network client: Digitally sign communications (if server agrees).
k. Click to clear the Define this policy setting check box, and then click OK.
12. Run the Group Policy Update utility (Gpupdate.exe) with the force switch. To do this, follow these steps:
a. Click Start, click Run, type cmd, and then click OK.
b. At the command prompt, type gpupdate /force, and then press ENTER.
Policy Update utility
Note: The Group Policy Update utility does not exist in Windows 2000 Server. In Windows 2000, the equivalent command is secedit /refreshpolicy machine_policy /enforce.
13. After you run the Group Policy Update utility, check the application event log to make sure that the Group Policy settings were updated successfully. After a successful Group Policy update, the domain controller logs Event ID 1704. This event appears in the Application Log in Event Viewer. The source of the event is SceCli.
14. Check the registry values that you changed in steps 1 through 7 to make sure that the registry values have not changed.
Note: This step makes sure that a conflicting policy setting is not applied at another group or organizational unit (OU) level. For example, if the Microsoft network client: Digitally sign communications (if server agrees) policy is configured as "Not Defined" in Domain Controller Security Policy, but this same policy is configured as disabled in Domain Security Policy, SMB signing will be disabled for the Workstation service.
15. If the registry values have changed after you run the Group Policy Update utility, open the Resultant Set of Policy (RSoP) snap-in in Windows Server 2003. To start the RSoP snap-in, click Start, click Run, type rsop.msc in the Open box, and then click OK.
In the RSoP snap-in, the SMB signing settings are located in the following path:
Computer Configuration/Windows Settings/Security Settings/Local Policies/Security Options
Note: If you are running Windows 2000 Server, install the Group Policy Update utility from the Windows 2000 Resource Kit, and then type the following at the commmand prompt:
gpresult /scope computer /v
After you run this command, the Applied Group Policy Objects list appears. This list shows all Group Policy objects that are applied to the computer account. Check the SMB signing policy settings for all these Group Policy objects.
Hope this helps.