Why does my display keep turning off every 10 minutes?

I have installed Ubuntu 11.10 (Oneiric) in VirtualBox as well as virtualbox-guest-additions. The display resolution adapts to the size of the window as expected, but the display turns off after 10 minutes of inactivity. Thinking there was some sort of power management issue at play, I went to Power in the settings dialog:

There doesn't really seem to be anything there that mentions "turn off display after xxx minutes" so I assume everything is configured correctly there. Next I went to Screen and found an option there "Turn off after:".

Aha! I thought. Now I have found the option - but alas: even after setting it to "never" and restarting multiple times, the display still shuts off after 10 minutes.

What am I missing? What option am I overlooking?

I note in the comments section that you have turned off power management.

Possibly you have run

gsettings set org.gnome.settings-daemon.plugins.power active false

Have you been playing with the alternative power management software xfce4-power-manager ?

Running xfce4-power-manager & via a terminal or xfce4-power-manager via startup applications, you can change when the monitor turns off - by default it is 10 minutes...

i.e. running xfce4-power-manager-settings

If you want gnome to be the default power management run

gsettings set org.gnome.settings-daemon.plugins.power active true in a terminal.

The blanking of a screen after 10 min is always suspect of DPMS & there were issues during 11.10 dev concerning that. But those where fixed & normally with the settings you've shown the screen should not blank.

Maybe this is a virtualbox issue - does your host Os blank after 10 min?

I guess you could additionally try this though shouldn't matter

gsettings set org.gnome.desktop.screensaver idle-activation-enabled false

And again no reason to but you could increase the time to idle

gsettings set org.gnome.desktop.session idle-delay 2400

A times in the past some have had to resort to an xorg section though again shouldn't be needed, could edit one in as a last chance ..