Problem Ejecting USB Mass Storage Device

Problem:

Could not unmount USB device.  Receiving error message

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Problem Ejecting USB Mass Storage Device
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The device 'Generic volume' cannot be stopped right now.  Try stopping the device again later.
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OK  
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Solution:

Download tool called "unlocker" and choose the drive which you want to unmount.

http://download.cnet.com/Unlocker/3000-2248_4-10493998.html