You may encounter strange warnings like the following if you develop WPF applications in Visual Studio 2008 SP1.

The type 'ConflictTest.MainWindow' in 'C:\ConflictTest\ConflictTest\MainWindow.xaml.cs' conflicts with the imported type 'ConflictTest.MainWindow' in 'c:\ConflictTest\ConflictTest\bin\Debug\ConflictTest.exe'.
Using the type defined in 'C:\ConflictTest\ConflictTest\MainWindow.xaml.cs'.

These warnings can be happened when you end a Visual Studio Process of which WPF designer is hanging.
To solve this problem, you have to remove a self-reference the Visual Studio adds by some reason.

Remove the executable assembly in the reference list.