Hi there jeff kim,
That is really unpleasant.
🙁
As CountMikes suggested, you can attach the drive to another computer with a different cable.
In case the issue persists, you can try the Ubuntu Live CD approach, as it seems that your system hangs when trying to access the drive. You will need a flash drive or a CD which you can boot(don't install, just boot from it) from. Here's a thread on that:
http://www.tomshardware.co.uk/forum/267999-32-recover-data-mode
Then, you can navigate to your external drive and see if it would be accessible. In case it is, you should really back up the data stored on it ASAP.
After that, you can switch back to Win and try to run both short and extended DLG tests on the drive...