SCSM 2012: Error when trying to unregister data warehouse. What to do?

Hi,
I have installed SCSM 2012 on two servers and all databases are in SQL on the Management Server.
SQL has installed on the Data Warehouse server and tried to unregister from the current data warehouse so I can re-register.
I keep getting an error message as I try to unregister. It has been attached below.

Microsoft. EnterpriseManagement. UI .Core. Shared. PowerShell. PSServiceException: A positional parameter cannot be found that accepts argument 'Help'.at Microsoft. EnterpriseManagement. UI .Core. Shared. PowerShell. PSHostService.executeHelper(String cmd, Object[] input)at Microsoft. EnterpriseManagement. UI .Core. Shared. PowerShell. PSHostService.Invoke(String cmd, Object[] input) at Microsoft. EnterpriseManagement. ServiceManager. UI. Administration. DWRegistration. Unregistration. DWUnregistrationHelper. Accept Changes(WizardMode wizardMode),
Help me to fix this please.
Thank you.
