I recently updated my Minecraft Launcher, and v1.7.2 of the game appeared in the drop-down menu of which version to play. The version I played before updating the launcher was v1.6.2 without any issues.

So installed the new version in the launcher and then tried to run it. When I press play the "wait" icon appears on my cursor for a second then goes and nothing happens. I left it for about 10 minutes before retrying.

I then pressed the force clean button and it updated the game files automatically. When I tried to run the game the same thing happened. I went back and selected v1.6.2 and the launcher ran it straight away.

I can't figure out why v1.7.2 of the game won't launch?