Go to Administrative tools/Domain Controler Security Settings
Open the Snap-in "Local Policies",
Go to "Security Options".
Search this string "Microsoft network server: Digitally sign communications (allways)". Set it to "Disable" .
After that restart the server...... ARRRGH !!! Or Wait 15mn !! To refresh the policies !!!
OR open a shell window and type this command lines to refresh the Security policies :
Windows 2000 : secedit /refreshpolicy MACHINE_POLICY
Windows 2000 : secedit /refreshpolicy USER_POLICY
Microsoft has replaced this command in Windows 2003 and XP with the command
You can run this command without any switches to update both machine and user policies. When you run Gpupdate on Windows 2003, the machine will display the following text:
User Policy Refresh has completed.
Computer Policy Refresh has completed.
To check for errors in policy processing, review the event log.