Snapshot 14w25a and 1.7.10 pre-release 4 Do not download properly

When downloading the new snapshot and pre-release the game freezes

What I expected to happen was...:
The blue loading bar would go all the way after I hit the play button, then the minecraft window would be brought up.

What actually happened was...:
The loading bar finished, but the play button became greyed out and the minecraft window never opened.

Steps to Reproduce:
1. Make a profile with the 1.7.10 pre-release 4 or snapshot 14w25a
2. Hit the play button
3. ...