I have had a usb HD plugged into my WDTV for a couple years. I upgraded the firmware to the new version yesterday and all seemed to be well. Today however i turned on the unit and whenever it tries to connect to the USB HD the system reboots over and over until i unplug the hard drive from the system.
Without the HD plugged in it boots up normally.
Media library on or off does not seem to affect the rebooting.
The behavior is exhibited with either the front or the rear port.