Silverlight: Why do I get 0x8000ffff when using WriteableBitmap on an Element

I'm working on a WP7 library which helps analyze your VisualTree and to provide a visual aid, I take WriteableBitmap snaps of the elements. Unfortunately I (seemingly) randomly encounter the following exception: A first chance exception of type 'System.Exception' occurred in System.Windows.dllWhen digging into the exception you may find that the error is actually a HRESULT which is being bubbled