Working with VS 2013 Preview and TFS + Git

I am trying to get into the new technologies and the goodies of the Visual Studio and TFS + Git, then I started to follow the ASP.NET MVC 5 Introduction Tutorial and connect this project to the free TFS account using Git, but every single time that I make a change in VS I get this message:

This file has been modified outside of the source editor. Do you want to relaod it? 

with the 'Yes', 'Yes to All', 'No' and 'No to All' buttons.

How can I avoid this message ?

Thanks in advance