The Hoster program should stay where it is. Only the songs should be moved. After moving the songs to the external drive, rebuild the database using the new song location and you'll be ready to go.
Loading programs on an external drive is not a reliable way to do it, and besides if you are thinking you can move the program from computer to computer by having it on the external, that won't work (although you can move the songs computer to computer in this way).
Sam
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