Don't ask me how it happned, but when I click on the Render Menu it says:
// Error: Cannot find procedure "MayaWindow|mainRenderMenu". //
also, another thing, now I have a new Shelf tab that looks like the attached picture. I didnt make it either. Now when I try to render anything, it just shows me a black window and does not want to render...
2 days ago it was just fine..