Could not load the file or assembly Microsoft.Crm.Core.WebServices

After installing update roll up 12 the plugin registration tools fails to connect.

The trace of this reveals the following error:

ExceptionString>System.IO.FileLoadException: Could not load file or assembly 'Microsoft.Crm.Core.WebServices, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Either a required impersonation level was not provided, or the provided impersonation level is invalid. (Exception from HRESULT: 0x80070542)

>File name: 'Microsoft.Crm.Core.WebServices, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

>   at Microsoft.Crm.Sdk.V5.DiscoveryService.Execute(DiscoveryRequest request)

1. I have uninstalled and re-installed UR12 and rebooted

2. I have tried both the old plugin registration tool and the new pre-compiled version in the new SDK, both produce the same error.

Currently in the app.config, there is only one assembly binding redirect:

   <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">

     <dependentAssembly>

       <assemblyIdentity name="Microsoft.Crm.Sdk" publicKeyToken="31bf3856ad364e35" culture="neutral" />

       <bindingRedirect oldVersion="4.0.0.0-5.0.0.0" newVersion="5.0.0.0" />

     </dependentAssembly>

   </assemblyBinding>

Not sure where else to go from this point.