This is my first (and, hopefully, only) issue.

Next to my desktop PC with Ubuntu, I now run Xubuntu (8.04) on an old Compaq Armada E500 (meaning: a Pentium III 500 mhz, 256 mb RAM and an Ati Rage Mobility).

Everything works fine - but I have the small, following thing going on: when I don't use the keyboard (i.e. when I don't type) for 1 minute or so, then the screen turns black. When I press a key, the image appears again (so, Xubuntu does not reboot or anything).

I noticed this only happens when using battery power, and not when using A/C power.

I also noticed that this already happened while I was installing Xubuntu, 4 days ago (so, it is not a Xubuntu setting?).
But this did not happen when XP Pro was still installed (so, a BIOS setting? But I don't see/recognize anything in the BIOS about this).

I have already read other threads about the Power Management settings and the Screensaver settings (the latter saying "Put the display to sleep when inactive for 30 minutes"), but these settings are simple and don't stop the screen from becoming black.

Has anyone any idea, as this is quite a bit annoying (but not a real problem).