can't unmount usb hd

[Robert Holtzman]

I have a 360 Gb external drive. When I back up my system (that has 3 
linux distros installed) with Clonezilla, the drive appears mounted as 7 
separate disks (/media/disk, /media/disk-1 thru /media/disk-6). That in 
itself is weird but isn't the main problem. The real hangup is that I 
can't unmount any of them. If I run umount as root on them the icon 
will disappear from the desktop but /etc/mtab and "ls /media" both show 
them all as still mounted.

Can anyone give me a hint?

-- 
Bob Holtzman
"If you think you're getting free lunch,
  check the price of the beer"