Ok. So after a month of having my 9930, I allowed the battery to drain to around 20%... when i plugged it in to charge and left it, I came back to see the red light flashing slowly. It wouldnt respond or power up. So I did a battery pull, and viola! it started back up again. since that day, I have refused to allow the battery to drain anywhere below 30%. I bought a car charger, extra usb cable and kept my laptop where ever I go. Haven't had any problems since. I'm still running 7.0.0 since Sprint hasn't offer any software updates....
but my fear of letting the battery run low is ********! why no word from RIM about this? is it the phone's hardware, the software or the battery itself?
I would try it again and see. What's the worst that can happen? It becomes un-recoverable and you get a new one. I couldn't live with the constant fear of dropping below 55 and boom! Oh wait, that's something else.
Anyhow, if you can't let it drop below 20% without it freezing, there's something wrong with it and you should take steps to duplicate the error and get a new one now. Don't settle.