.NET error loading in bootcamp - even with net 3.5?

Hi I'm running Rhino 4.0 in Windows 7 on an iMac via Bootcamp.  I've just updated Windows 7 (32-bit, SP1) and it shows me in the "programs and features" that NET framework 3.5.1 is running.  I'm also running the latest Rhino 4.0 - I checked today.  Also the version of Grasshopper I downloaded today says 20120928 - I assume it's the latest. 

Grasshopper installed fine, but I get this error message when I run it from the command line in Rhino:

Rhino .NET Error: Unable to load DLL 'rhcommon_c': the application has failed to start because its side-by-side configuration is incorrect.

I think I've tried everything I've seen the other people with a similar error trying in the forum.

Any suggestions?

Thanks from San Diego.