Expression of type 'System.Data.Linq.Table(Of xxx)' is not queryable
I don't recall getting this error so often in Visual Web Developer 2008 Beta 2 or the release candidate:
Expression of type 'System.Data.Linq.Table(Of xxx)' is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider. It popped up several times while checking the code for ASP.NET 3.5 For Dummies against the release version of VWD.
The fix is as simple as following the error message suggestion; import the LINQ namespace:
<%@ Import Namespace="System.Linq" %>