Late in the morning yesterday, I noticed that my battery was a little drained for having just fully charged it overnight. So, I plugged it into a USB cable off of my computer to top the battery off. I noticed a little while later that it wasn't really charging. So, I decided to reboot it, thinking that possibly the GPS was somehow still running or something else was continuing to drain the battery. After I rebooted, it showed right away that that battery was critically low and started periodically displaying notifications as well as making an increasingly annoying "chirping" sound to remind me that my battery was critically low. Well, I tried a bunch of things: restarting multiple times, syncing with Zune, charging with a wall charger - to no avail. I let it run all day today leaving the screen on for long periods of time to attempt to drain the battery. It lasted all day, even when running an exercise app that uses GPS. So, the battery was fine. Finally, I found an article where some people reported that removing the battery for a few minutes and then restarting fixed their problem. It fixed mine as well, thankfully. It's just one of the joys of using a brand new product. I'll report back if I experience any similar problems again in the future.