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I have a WD external USB hard drive. Most of the time it works fine (on Ubuntu).

Sometimes it will spontaneously stop working after an indeterminate amount of time. This happens more often after a suspend/hibernate than a cold boot. A cold boot always fixes the problem.

dmesg typically has no new lines when I unplug/replug. The device doesn't appear in the tray as normal.

The problem is more frequent on what I believe is the USB 3.0 port than the USB 2.0.

I have put the BIOS into legacy mode in order to dual-boot. The machine is an Alienware M17x. If I boot it with the hard drive plugged in then the initial BIOS screen loading bar usually stalls for a random amount of time. This never happens when the hard drive is unplugged.

I think the hard drive is physically OK. No unexpected stalls, noises, or data loss.

Any idea what might be causing this? When there is nothing in dmesg how do I start debugging?

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