ok, parece que o problema foi resolvido após a desinstalação do KB968389 ( ref ) e, em seguida, reinstalar novamente. isso me deixou perplexo por alguns meses, eu nunca teria imaginado que era relacionado ao NTLM ...
para citar:
If you capture network traces while trying to access shared folders, you may see a response of Error, Code =(13) STATUS_INVALID_PARAMETER from the server for the session setup:
192.168.0.2 192.168.0.1 SMB:C; Session Setup Andx, NTLM AUTHENTICATE MESSAGE, Workstation: WRK001
192.168.0.1 192.168.0.2 SMB:R; Session Setup Andx - NT Status: System - Error, Code = (13) STATUS_INVALID_PARAMETER
This error code means that there is an issue with NTLM authentication. The update in KB 968389 introduces a new feature that enhances protection and handling of credentials when authenticating network connections by using Integrated Windows Authentication.
This behavior can occur if the update discussed in KB 968389 did not install properly. To correct the issue, please uninstall the update completely and then reboot the server. After the restart, you should find that the symptoms no longer occur. Reinstall the update from KB 968389 and restart the server again. The issue should not re-occur. You should be able to access all shares successfully locally and remotely.