Not sure if this is a froyo or battery issue or? Last night I had my evo plugged in to charge overnight like I do every night. It was plugged in to a usb outlet in a power strip. After a couple of hours of being plugged in, it started making a loud noise that sounded a little like a siren...separate tones as opposed to one, constant sound. The screen said, "full battery," and it stopped as soon as I unplugged it. Any ideas about this? Thanks for any help!