When I put my bold on charge it almost instantly reboots itself. Sometimes it will be reboot itself again and again whilst still booting up. This can happens 5 or 6 times in a row.
When not on charge my phone is totally fine.
I have been charging my phone at night and in the morning it is usually charged up (even if it does reboot constantly) however the other morning it had not charged.
It also does this when I have tried to charge over USB (connected to my iPod usb mains adaptor) so it's not the charge.