I am by no means an expert on the launcher, and its pretty likely that danpaul is the only one that can say for sure what caused this, but I like to poke around and stab in the dark and see what I can learn So tell me, did you run as admin or otherwise grant it admin access in a UAC prompt? Because (this is a pure guess) it seems like these two lines refer to the actual ability of the application to start and do anything at all.
at System.Windows.Application.Run()
at W3DHub.Launcher.App.Main()
If the program failed on these (along with the few dozen other errors) then the PC tech in me screams "perms". There are some funky situations in windows where apps can attempt to run but any elevation prompts will be suppressed or denied by default, even if you right click and run as admin! It can silently deny it. Just a guess again, but I would think that could cause an error of this sort. Why that would happen but then not happen later, and the program be allowed to run normally is beyond me though, unless you changed some security settings.
Do you by chance have an "over-zealous" antivirus?