Dear friends:
I have, I believe, configured my screensave properly in KDE, but after the 60 minute period, the screensaver does NOT come on. Instead, the monitor turns dark and the green light turns yellow, making it seem that the monitor and the computer are off.
You probably also have a 60min timeout for putting the monitor to sleep. Have a look in your power settings (under power control) and set the monitor sleep to something > 60 mins.
Simon.