M-Power ProTools FastTrack USB unit won't work

Hi all. I'm using M-Power Pro-Tools Essentials software version 8.0.3 with a USB inputter, the Fast Track M-Audio guitar / mic recording interface. When connected via USB to my 21 inch Intel Mac it shows a blue led power light and a green led signal light. I've recorded on it once before with no problems, but recently it has failed to register any signal on the software interface. It's only about six months old, bought new and has been used once as a test by me.
When first connected both lights glow; then after about three seconds the green light goes out. If I unplug it, Pro-Tools immediately tells me that it's disconnected so it's being registered. If I go to system preferences, it appears as an icon, but on opening the icon I get the message: "Settings will be applied to a device as soon as one is connected". This almost immediately changes to "A device is connected. Settings will be applied to it immediately". However there is no change at the input device and no confirmation green signal light. If I close the preferences window and reopen, I get the same message again.
I've downloaded the most recent drivers and all software is up to date.
It appears the connection is being dropped almost immediately on startup, restarts of both computer and software make no difference. I can't think of any other settings on the Mac to try.
Any thoughts?

Binned it and bought a Firewire Profire which works perfectly. Another case of old hardware now abandoned by the manufacturer so no support or help for the earlier model.