Original reporter: light11184
When device have lost(ex. lock windows(Press Win + L)) my program was wanted clear viewport and call viewport::clear() function.
At this time the program has crashed in D3D9RenderSystem::_getDepthStencilFormatFor() function. line 3755, because variable mSurface is null.
I guess must check whether device was lost, or not.
Original Mantis Ticket: http://www.ogre3d.org/mantis/view.php?id=478