Unable to eject or erase USB drives I'm unable to eject USB drives. When I try, I get this error:


  The disk "Untitled" wasn't ejected because one or more programs may
  be using it.
  
  To eject the disk immediately, click the Force Eject button.


Additionally, when I use Disk Utility to erase a USB drive I get this error:


  Disk Erase failed with the error:
  
  Couldn't unmount disk.


This happens on my account and my wife's account. I can partition USB drives, but I can't erase or eject them.

Any ideas on how to resolve this?
You can use lsof to list open files:

sudo lsof|grep /Volumes/Volume\ name


If you run lsof without sudo, it doesn't include processes owned by other users.