Compiling error with DataGrid in Beta2

Hi,
I finally got everything (well, almost everything) compiled in beta 2. Only one thing left is the DataGrid.
I got compiling error with DataGrid in beta 2. If my Silverlight project has no UserControl uses DataGrid, then everything is compiled and runs fine. But if I add a UserControl, then add a DataGrid to the Xaml, then I got following compiling error:
"Derived method 'OnApplyTemplate' in type 'System.Windows.Controls.DataGrid' from assembly 'System.Windows.Controls.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' cannot reduce access. "
I created a new Silverlight project with the only default Page.xaml in it. Here is my Xaml, nothing in the code behind.

<UserControl
    xmlns:my="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data"             
&nb ...