I have been using an external hard drive for some time now and recently my computer has stopped recognizing it. I open system profiler and it does not show up under the usb category. After about 4 days of not being recognized, I tried to use the hard drive on a PC and en error message came up when I plugged it in saying something about a malfunction. A couple days later, it suddenly came back for about two days and now it is completely gone again. Is there any way to fix this? Is it a problem with the usb cord? I am sure that my usb port is working because I have tried other hardware there. Thanks.