That is very weird; but permissions shouldn't keep you from mounting the disk at all.
I know it says that you don't need to repair the disk, but I guess the next steps are:
1. Use "Repair" on Disk Utility.
2. Buy or Borrow a copy of Tech-Tool Pro and try that.
3. If those two don't work, give up and repartition and reformat the disk.
4. If the reformat doesn't work, go back to where you bought the disk and get your money back.
Wait - I have one last thing you can try, but it requires the Terminal again. I used to see this occasionally with external disks and 10.2. This is also slightly risky, but it may solve the problem IF the problem is with your Mac and not the drive:
1. UNPLUG ALL EXTERNAL DRIVES - make sure the disk is NOT connected.
2. Open a new terminal window.
3. Type the following command. Do NOT type "exit".
ls /Volumes
4. If you only see your built-in hard disks you're okay; stop here. If you see "Nickels Backup" EVEN THOUGH THE DISK IS DISCONNECTED then try this:
sudo rm -rf "/Volumes/Nickels Backup"
Make sure you get that command exactly right! This is the UNIX delete command and deleting the wrong volume could seriously ruin your day - as in "erase your hard disk".
5. Reboot. Try plugging the drive in again.