I get the following error:
Undefined CLR namespace. The 'clr-namespace' URI refers to a namespace 'WpfApplication1' that is not included in the assembly. D:\Programming\VS10Projects\WpfApplication1\WpfApplication1\MainWindow.xaml 4 21 WpfApplication1
When referencing the same project in a XAML (i.e. xmlns:local="clr namespace:WpfApplication1") to place a user control or other type of control on a designer window. The program builds correctly and runs correctly but the designer fails.
Switch to 32 bit and it works fine.