Unrecognized tag prefix or device filter 'asp'

Hello,

1) Using VS 2010 SP1. I'm getting this warning on some pages: "Unrecognized tag prefix or device filter 'asp'. ", and intellisense no long works for <asp: /> items? 

2) Also getting this warning on things like <ContentTemplate>: "Validation (XHTML 1.0 Transitional): Element 'contenttemplate' is not supported."

Anyone know how to fix these issues?