i always thought system variables are expanded in the registry but... ... i'll suppose your registry entry looks like "%Install%\App.exe", the variable %install% it's defined during the runonceex importing process, but what about after reboot? i think i'm not explaining too well, after the reboot, when runonce process it's started, it finds a "%install%" entry but it isn't defined bcuz after the reboot, you haven't stablish it