The side USB ports on the i-945 and iOne-GX31 are not designed to accommodate the current supply required by an external hard drive. For best results, use one of the USB ports on the underside of the unit. If this does not help, a few options are available.
1. First, try using a USB cable with two plugs on one end; the single end connects to the external hard drive and the end with two plugs connects to the bottom USB ports. One of the extra USB connectors will be dedicated to providing power to the device while the other will carry data.
2. For especially power-hungry external hard drives, an external USB Hub with its own power supply is recommended. Some external hard drives may require an AC Adapter; check with the device's manufacturer for further information.