hmmm... I allways add it to the autostart.sh, but perhaps one of the machines has loadet it into the lxsession-manager (root menu -> system -> Services/Daemons) and the other has not... check both machines if it's there. if it is delete them, add it to the autostart.sh
Sleep is in the autostart, it gets the program to load after other programs in case it needs another program to fully load before it can function... see the autostart and you'll get the picture... if not I think there's a wiki entry for autostarting.