Visual Studio 2010 Conversion issue not recognizing prefix 'asp'

I just converted a project from Visual Studio 2008 to 2010 and all of my asp c开发者_Python百科ontrols have a warning stating..

Unrecognized tag prefix or device filter 'asp'.

It also is not showing any intellisense, anyone else experiencing similar issues? Is it possible my conversion did not go through correctly?

Thank you.

I too was having this issue, I resolved it by deleting the C:\Users\UserName\AppData\Roaming\Microsoft\VisualStudio\10.0 folder