The initial reporting has been contradicted. The mobile message was a hoax; contrary to what Greek authorities claimed, most passengers were alive when the plane crashed, not frozen.
And related to the Paine Stewart crash: the windows were not frosted over. The F-16 pilots had a clear view into the cabin and the cockpit. So the decompression theory may need some amendment.
Latest reports have it that the plane crashed due to a lack of fuel. Given that it crashed at about the same distance at which it was supposed to land, that was cutting it awful close. So even without the air supply problems, this flight had a good chance of getting in trouble.
Right now, this is a complete mess and no one has any clue what went wrong :(