Falling on your back when you deshift

Not sure if anyone experienced it, but I ran behind a corner to heal, and when I deshifted, became encumbered and ended up on the ground.
Restoration didn't help, FoM didn't help and I didn't fail any spell either...
Happened to me for first time.

What is even worse is when your hp is low, and you auto reshift. And low hp causes a death... semi high hp causes a free heal...

(Sometimes you do the shift animation without selecting a form to change into or unchange into while polymorphed... the server just refreshing you automaticly -You'll know what I am talking about if you spent a lot of time in a shape.)

I think in your case the reason that happens is the Con change from normal form to which ever form you use.. (I'll assume dragon) -Same thing would happen if someone has low hp surviving on a Con Buff and the con buff wears out or gets dispelled.
However, I don't remember if it's buggy, perhaps the buggyness only happens when shapechange is involved.