Probably the partition table is corrupt. When it does this, it becomes difficult to
unmount (actually it gets stuck in a loop trying to mount the file system, to no avail
because the file system is corrupt).
This procedure forces a dismount, but does not eject the drive.
This breaks the loop and allows erasing the partition table:
open terminal.app
note: I wrote these instructions were for a boot volume
with that condition (booting from the install DVD), so the
disk numbers are not going to be accurate.
at the prompt:
diskutil list
(press enter)
that will give you the device name of your drive.
It most likely will be "disk0".
next command:
diskutil unmount force /dev/<disk_name>
example:
diskutil unmount force /dev/disk0
next command:
diskutil zeroDisk /dev/<disk_name>
example:
diskutil zeroDisk /dev/disk0
(press return)
After disk is zeroed, you may resume normal partitioning.
#
Bear in mind, since this is an external disk, the USB/ translation layer
may interfere with accessing the disk directly and foul up the procedure.
Looking at the drive specs, it says it only supports use under windows,
whatever that means. Perhaps it requires a proprietary USB driver or something.
Some folks claim it works on a Mac though.
http://techpatio.com/2010/reviews/hp-simplesave-2tb-usb-launcher-mac-blue-led
The USB interface (inside the unit) might be hosed.
Sales poop says it has a two year warranty. If still in warranty, send it back.
Kj