sarov - 2015-10-11

hi,
I am repeatedly getting this error like,
Could not load file or assembly 'Google.Apis.Authentication.OAuth2, Version 1.2.4696.27633, Culture=neutral, PublicKeyToken=bc5738hukl' or one of its dependencies. The system cannot find the file specified.

I tried all the said steps inc moving the plugin cache files, editing config.xml and fresh installations and starting up all together, but get the same error repeatedly. I donno what that public key token is, or how to take that off.
what am I doing wrong?