Started up Steam, noticed it doing a download of something - didn't see what. Now every time that I try to start Skyrim, either through NMM or directly through the opening screen it's immediate CTD on the Bethesda logo screen.

Not installed any new mods since last time that I ran it, so my suspicions are on whatever the sneaky download was.

Anybody else with similar probs?!?

Try to uninstall all mods before starting the game. Not every mod are compatible with the newest version of the game.