Maybe it is one of those features that is killing you. I assume you have already checked to ensure it is not the midnight turn-on and houskeeping that is causing the battery problem? I don't know about the 5455 specifically, but I know that turning on with a Wifi card in the machine can establish an AS connection that won't allow the connection to drop and the device turn off in some devices, depending on settings. I suppose BT could do the same.
Can the radios be set to OFF, so that they won't be transmitting and potentially establishing a connection if the device should turn on, due to a schedule, alarm, or even an accidental button push (you do sleep with your PPC don't you
)