Minecraft not downloading or launching

When I try to download the latest release of minecraft, 1.7.4, the download bar fills up but doesn't start the game. When I hit play it downloads again and doesn't start. This happens in an infinite loop.

I thought that once the version of minecraft was done downloading it would auto start the game.

The game does not start and I have to hit play, but when I do the download bar fills up again and doesn't start.

I guess try using my version of OSX to download minecraft 1.7.4