We are using RadGrid quite extensively in one of our projects and as we moved to Visual Studio 2013 basically the rendering of all of them crashed. Some grids stopped outputting a table altogether, others justs rendered wrong.
This only happened in VS2013, not in 2012 and not on servers where we deployed. Finally we tracked it down to the new BrowserLink functionality in VS 2013. Once we disabled BrowserLink in appSettings in web.config everything started working again.