Hi,
Since upgrading from VS2010 to VS2013 I'm getting a lot of green underlinging (warnings) of markup code. The message says that known elements (content, DropDownList etc) are not known elements when obviosly they are, or that there might be a problem with the web.config which there is not.
This just happened a few moments ago when no changes had been made to markup.
I would just ignore this but it stops intelli-sense from working. 
Any ideas?