I had the exact same issue, game ran fine yesterday, started skse (thro shortcut as anjen was suggesting, thats always how I start my skyrim) today it would either get to title screen and ctd after a couple seconds or it would flat out ctd right before the logo. I ruled out modding as I didn't change any file, no skse/skyrim update either. I always keep an entire backup of a previous stable skyrim install just in case some modding goes wrong, booted that one up, exact same issue. Started looking around, people are complaining about similar issues after latest win10 update (yay microsoft as usual) but I actually havent updated that yet, been putting it off for nearly a month so thats not the issue. After that i remmebered letting steam update itself either yesterday or the day before. Curiously enough, the ctd we're experiencing happens at the same time the steam overlay starts up (4-5 seconds in), so i figured I'd check for another steam update, there was one. Had steam update itself again and the issue seems to have gone away, so my bet is the steam overlay was causing the issue and that was fixed in the last update. Give it a shot.