Hi. I'm converting my own web browser use WPF from Windows XP to Windows 7. when I test on Windows XP, It has no error and exceptions. But I convert and test on Windows 7 with Multi-touch Library, My Browser occurred unhandled exception. Source: PresentationCore Message: An unspecified error occurred on the render thread. StackTrace: at System.Windows.Media.MediaContext.**NotifyPartitionIsZombie**(Int32 failureCode) at System.Windows.Media.MediaContext.NotifyChannelMessage() at System.Windows.Interop.HwndTarget.HandleMessage(Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) InnerException: null I want to know where the bug occurred. That Trace Message are garbage information for me. I already googling to know that message, but i never found any information. How do I get exactly function where the bug occurred? please tell me something.