Hi, i have this Asus n76vz and when i plug the external hard drive, no matter what port, the port sparks. But still once i plug it it works, except that after i unplugged it, that port stopped working with another hd, and a 64 gb pen drive. But it worked with another pen drive. Then ' rebooted and it worked again as normal, but it still sparks when plugging that hd. I think it something in the external hd, maybe the cable. What do you think?
Same happens on Lenovo. In my case, both devices had to be powered to see the sparks.
To fix it, I fashioned an earth by taking another usb cable, plugged it into an unused port on the hub, cut up the other end and connected the sheath within to earth (note that some cheaper USB cables have only 4 wires and no sheath).