6.5.16 Outlook Plugin Error - "The Sugar Server Specified in Tools -> Sugar Options Is Unavailable"

After upgrading our sugar from 6.4.6 to 6.5.16 yesterday our Sugar Outlook Plugin stopped working. When testing the connection an error is thrown "Options is Unavailable". When looking in the log for the Outlook Plugin there are unexpected end of file exceptions in the CheckServerVersion method.

We have tried to reinstall the plugin with out any success. Any Suggestions?