So I was pretty stoked to get my Halloween update on today, but there seems to be something wrong with the updating screen. Every time I try to launch the game, It tries to update, but the progress bar stops at 41%, and says "Failed to launch, Fatal error occured, blah blah blah, (Access is denied) Has anyone else had this issue, or know how to fix this?

Maybe. It could be that the server is still overloaded, or something. You can download another .exe for Minecraft I think.

Are you still having the problem? I was going to suggest it could be some custom visual pack you installed, but I had one and mine updated just fine. So I have no idea.

Its still happening, I tried downloading the .exe, but I will try it again.
 
Edit: Still doesn't work

" Its still happening, I tried downloading the .exe, but I will try it again.  Edit: Still doesn't work "

Does that mean I will lose all my saves?

I think they are clouded, but you could make a backup of the "saves" folder inside the ".minecraft" one and once you've re-installed copy it back. Also can you use the browser version?

They aren't clouded, at least when I tried to play on a different computer my saves didn't appear. 
 
back up your saves.

Hey, I fixed it! Thanks a million, duders.