Stopping the monitor going into nap-mode

Can anyone tell me how to make the darn monitor turning itself off every 10 minutes when there is no activity? I have the screen saver set to OFF, and the power management set to IGNORE (off) but still the damn thing goes into standby mode - most annoying. And setting the screensaver to activate after 240 minutes has no effect- the standby mode still kicks in. Cheers. -- Don't argue with an idiot, people may not see the difference.