external hard disk issues


Beta member
so i bought a 300 gig external hard drive(maxtor) and mounted it in a aluminium qtec box(bought seperately). anyway i format the hard disk and everythings going great. it registers on my disk manager and i assume its all done.

so then i copy a load of films from my c: drive to this new drive(about 15 gigs worth) and go get something to eat. anyway upon returning the thing says that theres been an error and the transfer can't be completed. i then realise that this is due to my computer not even recognising that theres a external hard disk connected to it. i checked the USB cables on other things and they're fine, the power cable is fine because the red light comes on when i connect the power to the hard drive.

what would people say is the most likely occurence? that my hard drive has broke after about 5 minutes of getting it working? is there anything else that could be responsible?