Hello All! I'm getting this exception ('System.InvalidOperationException' ) when trying to run the Manipulators example (from Ziggyware site), Running stops at the line when issueing mesh.Draw(SaveStateMode.SaveState); method. This also happens at far simpler projects, such as a new windows game, that is only drawing a simple triangle. Draw command fails.. I've managed to discover than commenting the line "effect.LightingEnabled = true" solved this.. but why ?? Can this be GPU related? i'm using a laptop with a GPU that is less than SM 2.0... Any ideas? Lior.