Reply to smoker:
Your original answer was not to use system commands (like umount) as the names of custom scripts, if I recall correctly. If I try to run a system command from a desktop launcher without sudo I will certainly get an error, but it is usually possible to call ./<filename> (which will call a script in my home folder, whether or not it has the ".sh" suffix, which brings us back to the topic of recognizing file types) in desktop launchers even without choosing "Application in Terminal" (GNOME) or "Runs in terminal emulator" (lxshortcut), so that cannot have been the problem.
So your post was certainly relevant; I hope I have given a better answer now.
Last edited by nokangaroo; 06-25-2011 at 05:45 PM.