I have installed Ubuntu 10.04. I decided to create an additional account for people who come over and want to use my computer. I called this account "Guest". People have complained that when watching movies that the screen saver pops on every 5 mins and locks the screen on them and its annoying. I tried to go into the screen save utility but I am unable to access it from the guest account and it gives me the following error

Could not launch 'Screensaver'

Failed to execute child process "off" (No such file or directory)

I have tried given the "Guest" account administrative authority and that hasn't helped. Is there anything else I can try to change the screen saver settings?

Thanks