"High performance with low power consumption– The DSmobile 600 connects to a high-speed USB 2.0 interface yet only consumes 0.2W of power when in standby mode and a maximum of 2.0W of power when scanning."
volts x amps = watts
watts divided by volts = amps it draws
USB ports use 5.0 volts.
2.0 watts divided by 5.0 volts = it draws .4 amps = 400ma.
It MUST be plugged into a USB port that can supply the full 400ma of current.
The standard max a USB port can supply is 500ma, however, that only applies if the USB port is directly connected to the mboard.
If you have it plugged into a USB port in an external USB hub, it may not be able to get enough power, even if the hub is "powered" and has an additional power adapter connected to it.
Troubleshooting USB device problems
See Response 1:
You MUST install the software for the scanner the proper way.
READ the installation directions !