O/T sinister volume

[A Marshall]

sorry for being off topic, my problem is a disc mounting on my desktop 
every time i launch the application associated with it.  I originally 
installed the software from the mounted disc (volume) by dragging & 
dropping onto my applications folder, but every time i launch the app, 
the disc mounts back on my desktop?

any ideas? am i missing something obvious??

cheers
~a

p.s. i did try reinstalling