Hey, did you find out what was wrong, I seem to be having the same issue, don't want to waste half a day downloading/reinstalling again if there's a quicker fix. I'm using windows 8.1 My KSP installation was from windows 8 copied the steam KSP directory, installed the update, there are two sets of everything in "start". Can't select anything to get started. Chicken and egg science issue Okay, for any future kerbalers with this problem, I deleted (cut and pasted to an unrelated folder) all 142 "parts" from the KSP > Parts. This worked, yay!