EDIT: Well it looks like I was able to recover the unit by holding down the power button and hitting the reset key repeatedly while doing so. Left to its own devices the unit would sit there indefinitely at the JBL screen and never progress beyond it. Reset key and removing batteries did nothing (other than powering down the unit). There is definitely a problem but hopefully this method will allow easy recovery if this happens again. /EDIT
Darn... Mine just froze up the other night and stalls forever at the jetBook Lite screen as well. I've tried removing batteries for an extended time, and of course resetting the unit. Mine has 0.15d firmware out of the box.
I almost wonder if it could be a heat issue because I did read the thing for about 5 hours a night while it was working... Bummer.