Anyone managed to find the exact cause and perhaps a solution? I've looked up and found another thread (http://forum.kerbalspaceprogram.com/threads/122586-Editor-bug-with-fairings) talking about the exact same problem only the solution they gave him there was pretty much to be more careful with the fairings. Looks to me like the connecting the fairings unwisely causes some kind of error with handling the parts and makes the game think that the user is still holding a part or something, thus he is unable to click any other parts. Anyone who has more experience can try and verify my suspicions?