It is, in fact, insufficient power. Classic symptoms.
However, you may want to disable "USB selective suspend setting" - known to be a pain in situations like this. If it doesn't work get an external USB case for DVD that comes with extra usb-to-pin cable delivering extra power to the drive.
Like this: http://www.amazon.co.uk/StarTech-Slimline-Optical-Drive-Enclosure/dp/B003GSCS2G