why's everything black?

I just applied a material to my engine block and then all of a sudden everything turned black as a material except if I render it

Even when i make new objects like boxes or cylinders they turn black too

How can I fix this problem?

[Catlin]

something is ****ed up using either mental ray,vray or brazil just go to render tab or press F10 then at the bottom change the material editor thing(you will have to press the little lock thing next to it) and change it standard max,that should work

No, i got it to work, I had a omni and when I deleted it everything returned to normal so..