It looks like Mental Ray is not loaded, this is usual for Maya and only requires you to load it via Windows > Plug-In Manager
Look for mayatomr.mll in to list and click autoload and then load. Close the Plug-In Manager and you will now be able to render with Mental Ray.
Chris (formerly R@nSiD)
When the power of love overcomes the love of power the world will truely know peace - Jimmy Hendrix
Winner SM VFX Challenge 1
3rd Place SM SteamPunk Challenge (May 2007)