The comments on the original post are getting too long, so here is my answer.
I suspect that it's the drive itself. Maybe try update your Raspberry Pi and then try again.

To update
    sudo apt-get update &amp;&amp; sudo apt-get upgrade

Then try to access the drive. If this does still not work. I'd recommend trying to find someone with a HDD at least the same size or bigger and test that.

can I use a disk larger than 320 GB with RPi?
I recently installed Ubuntu Desktop on an older machine, and the performance isn't what I'd like.  I'd like to switch it over to Server (server kernel, drop the GUI, etc) with minimal hassle.  What's the simplest way for me to do this, preferably without re-installing from CD?
