I just installed the release version of Visual Studio 2010, and it looks like there's something wrong with the standard ASP.NET server controls.

When I create a basic server control, such as a TextBox, the editor underlines it in green and says (I also get no intellisense for ASP.NET controls):

Element 'TextBox' is not a known element. This can occur if there is a compilation
error in the Web site, or the Web.config file is missing.

The web site builds fine, and the Web.config file is not missing:

<?xml version="1.0"?>
<configuration>
<system.web>
  <compilation debug="false" targetFramework="4.0" />
</system.web>
</configuration>

The controls work just fine in the code-behind, and they function correctly when I run the site.

Is there some configuration problem here?