If the plugin doesn't work immediately after updating, you should just need to download and install the full .NET Framework 4.0:
http://www.microsoft.com/downloads/deta ... laylang=en
You can check whether you need this or not using Add/Remove Programs; it will be necessary if you only have the
'Microsoft .NET Framework 4 Client Profile' installed. If you have no .NET Framework 4 at all, then the plugin should still work fine, but Windows Update may still install the
'Microsoft .NET Framework 4 Client Profile' at any time; if or when that happens, the issue will appear and you will then need to download and install .NET 4.0 from the link above.
The issue has to do (if you haven't figured it out yet from reading the above) with Rhino 5.0 loading .NET 4.0 when it is available, and it presents a problem when the .NET 4.0 installed is the so-called
Client Profile, which is a reduced-size framework that excludes a couple of components required by the plugin.