okay it looks like you have backface culling of some short turned on but I am not sure why you are getting the triangulated mesh.
I know you said deleting prefs did not work but do this anyway
1. select everything in the scene and export it to a file xxx.mb
2. close maya
3. goto the documents folder (if you are running windows)
4. rename the maya folder to maya.bad
5. restart maya and open the scene file xxx.mb
If the problem is still there after all that then I have no clue what you have figured out how to break lol
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Please help me and sorry for my bad English. 
