You may encounter an issue using the CRM web service in Visual Studio (VS).  In VS, the web service is added using the "Add Web Reference…" button. 

The error message that's reported in Visual Studio is "Method 'XYZ' cannot be reflected" and "There was an error reflecting 'XYZ'".

 Here is the error that showed up in Visual Studio:




This issue can be caused by an incomplete upgrade from 7 to 7.1, where Email.emai_type and other similar fields still exist.

Once the fields are deleted, the errors should disappear from visual studio once you update your webservice reference.