Well, this "bug" is happening to me since 1.4 beta, but i never actually reported it.

What happens is that, the whole game freezes (mobs stop walking and stop doing their things, when i start breaking a block, the "breaking animation" doesn't happen, and there is no sound.), BUT i can still walk around, open doors, break blocks, etc... And, everything i do when the game freezes, it will revert back to normal when the game unfreezes.

I takes a long time to the game unfreeze, but if i can force the game do that, simply by going to Settings.