I've tried accessing this external hard drive through different usb ports and different computers, same result "I/O device error". I've tried formatting it using a windows XP disk but when I reach the screen where I have the option to delete partitions and create partitions, the computer reads the external hard drive as an unknown drive but I cannot do anything to it. I cannot select it to delete the partition or anything like that. This external hard drive was actually a old hard drive from my previous laptop. I just took it out and now I'm using it as an external hard drive. It worked fine before but i think the reason why I'm getting this problem was because my friend was using my hard drive and while it was processing something, he pulled it out. After that incident, this started happening.