It's just slower than the wall charger. I've noticed that it'll take all night to charge as oposed to a couple hours on the wall charger. Same with the USB charger for the truck.
The 2.1 release has the same bug/flaw/feature. I just got a PlayBook for my 15 year old (he likes it and I shopped for a cheap one). Both his and mine showed the same message when I connected to the PC. I don't rely on the PC to re-charge, but don't really want to lose charge if I'm copying files. I use mine at work to tach from so I am frequently moving stuff back and forth from my PC.
Same problem here, I have a notification on my PB that says "Unable to charge battery with connected source" I keep it plugged on standby and it really dont charge. weird.
Yes, the PB is charging, slowly. Strange thing is, that they removed the "plugged in electricity" icon. It was there in older OS, now it is gone, I don�t understand why, it was quite useful.
It's not suppose to as the USB isn't powerful enough, However, you are right. On Saturday, I left my Playbook at 20% battery in the hotel performing a backup. Upon returning at midnight, it was fully charged. Not that I would do this routinely. But it was nice to see.