Application Styling Configuration 10.1 is missing from Visual Studio 2010->Tools.  This is an error which can be fixed in the following way:

1) Open Infragistics.Web.ApplicationStylingConfiguration.AddIn found in "My Documents/Visual Studio 10/Addins," (that Infragistics created) and add the following lines above the first "HostApplication" tag and below the "Extensibility" tag:

 <HostApplication>
    <Name>Microsoft Visual Studio</Name>
    <Version>10.0</Version>
  </HostApplication>

2)  Add "My Documents/Visual Studio 10/Addins" to Visual Studio 2010->Tools->Options->Environment->Add-ins/Macro Security->Add-in File Paths

3) Restart Visual Studio 2010