i have a similar problem to one described in this question, though i don't feel it was fully answered, and I'd like to give a bit more detail specific to my case.
I had a western digital NAS ("my cloud") that stopped working. I read that if you removed the disc from it and put it in an enclosure you could access the files via a linux machine, as it is encoded in ex4.
I did this, borrowing my brother's laptop which is running ubuntu 13.10
When i initially plugged the hard drive in it mounted fine. My brother did some terminal commands to make one of the folders unlocked (it had been password protected on the NAS). After he did this, I was able to look at all of my files fine. I didn't transfer anything at this point and shut down the computer.
I've come to access my data again (a week later), and when I plug it in the drive is detected and spins up and ubuntu opens a window. I try to access my files but just get a loading wheel opening the first folder and then after 30secs or so the drive disappears and reappears, as if it had been unplugged and re-plugged. at any point during this cycle if i try and safely remove or unmount the drive i get a message saying that it's being used by nautilus.
the drive itself seems to keep humming/spinning throghout. I don't think it's a power issue as the caddy is powered by its own power supply. I've checked that the drive is still snuggly connected to the SATA connector inside the caddy.
other external hard drives mount and stay mounted fine. The caddy is well reviewed online, though replacing that is a next step i can think of.
is there anything obvious that I could do/am missing?
many thanks in advance