Bee Death

On my lunch today I ran home to make sure that the bees could get out of the hive for some nice weather flight and to put the sugar feeder on it until the pollen starts.  Sadly I found that the entire hive was dead.  Was it disease, starvation, succumbing to the extreme temps this winter or something else???  I had to go back to work so I didn't inspect it too closely.  When I got home I opened it up and took a very close look.  All the bees were dead but there were by no means all the bees in the hive (10's of thousands) but rather only 1000's of dead bees.  So what happened to them?  The frames in the hive were surprisingly VERY heavy with honey so it seemed that starvation was not possible. 
For long time readers of the blog you will remember that last summer my one hive (not by choice) became two hives and then I once again combined them.  Re-read that post here: http://czarofthewoodsfarm.blogspot.com/2010/10/bee-update-and-then-there-were-two.html
Thank you to my beekeeping mentor, Steve, for taking the evidence that I presented to him today and told me the following.  What most likely happened, he feels and makes great sense, is that when I had to re-combine the 2 hives into one at the end of last summer they never worked out who was to be queen.  This probably caused there to be no queen and many of the bees left.  Without a queen there is no reason to be there.  I also found a new queen cell hanging in the hive today which means that the bees that were left were creating a new queen by feeding her royal jelly so that she would become queen.  Sadly she never had a chance to emerge, perhaps due to cold weather.  Had she have perhaps they would have been okay but Steve also pointed out that since all the drones were gone there would have been no reproduction going on.  This would explain why there was so much honey and comb.  All the bees worked hard to make it but once they couldn't figure out the queen situation many left, the rest died, leaving it all behind.
Sadly I have to start over but when I order/purchase new bees they will be happy to find all that yummy food waiting for them.  Steve, thanks for all your help.  I would bee lost without your knowledge and willingness to help me with our bees.