Have you tried changing rendering subsystems?
You can do this by opening up the ogre.cfg file and typing the opposite rendering system next to "Render System=" If it is currently "Direct3D9 Rendering Subsystem", type in "OpenGL Rendering Subsystem" and vice versa.
You can change this ingame as well. I am only recommending this because it sounded like you were having problems and I wasn't sure if the user interface was affected by that.