Long story short - I recently installed Maya 2011 Trial edition, to test drive it, having had a great experience with Maya 2010, BUT since then I have had nothing but problems in regards to rendering. So I have opted to stay with 2010.
Now, the problem is that when I go back to Maya 2010, and try to render, I am now encountering problems there as well; specifically Mental Ray no longer reads the displacement in my displacement maps. This is not simply one file ether, this every file I have ever applied a displacement map to... Every other texture/file type seems to render out fine though - so the problem IS only with my displacement maps.
I have searched the web, and as far as I can see no one else has encountered a similar problem... SO I am open to any suggestions anyone reading this might have. At this moment I am uninstalling and reinstalling Maya 2010.
Again, any suggestions are sincerely appreciated.