I tried a lot of distros to bring my old Compaq N1020v laptop to life (it's got 512mb of ram): Lubuntu, Lucid Puppy, Mint, Gentoo, Salix, Damn small linux...
The original screen of the laptop is broken (the lamp doesn't work), so I've connected it to an external mointor.
Here's my problem: whatever live distro I try, after booting (when desktop appears) the external monitor goes into power saving mode and I can see the shapes of the icons by looking at the broken one.
The only one distro I can use is Damn Small Linux, but I don't want it.
How can I solve this problem?
I'm getting crazy. Maybe it's a stupid thing. Maybe it's not.
But in fact I can't use a laptop just for the power saving.

Federico.

Does turning ACPI off in BIOS have any effect?

try putting this line in /etc/X11/xorg.conf
under Section "Monitor"
Option "DPMS" "false"

might help

Thank you for your answers.
andrewthomas, I tried to run every distro with noacpi or acpi=off, but nothing happened.
gary185, excuse me for my ignorance, but can I put that by terminal in Damn small linux? That's the only one working OS...

I think that when X starts the signal isn't sent to the external monitor and it goes into power saving.

yea,
how is the external monitor connected?
basically all linux distributions are the same.
you just have to configure the display server to send the signal the the right device.

I would try it like this: Install a distro from its normal install CD, not a live-CD, best with text mode and see if it works to install it with an attached monitor. Make sure that an SSH-server is installed. For example, try it with Debian. After the install, when the monitor isn't working anymore, SSH into the machine and set up the xorg.conf the way you need to work with the monitor.

The external monitor is connected by regular cable...
TobiSGS, I've already done that: I've installed salix, based on slackware, but now I don't know how to edit xorg.conf if I can't boot the OS completely. I said, if I try to do it by the commandline of the salix cd:
/etc/X11/xorg.conf
I get a "not found" message...
I dunno, am I doing something wrong?

Modern distros don't come with xorg.conf by default. Create one withand copy it to your /etc/X11/ directory.

from the command line of the live cd you have to mount the hard disk partition the file is on to edit it
as root
mkdir /mnt/dslinux
mount -t <file system type> /dev/<whatever the partition is> /mnt/dslinux

the use of the /mnt/dslinux folder is arbitrary, it can be any empty folder
if you can't make a folder on the live cd just use any existing folder

then you can navigate
cd /mnt/dslinux/etc/X11

you will need to play a bit with the Xorg config until you get it
you need two "Device" sections, two "Monitor" sections, and two "Screen" sections
the device (video device) for both is the same but each need a separate section
here is an example config
http://ozlabs.org/~jk/docs/mergefb/xorg.conf

in the example the guy only references the internal screen in the "ServerLayout"
not sure why but it must work that way

under the monitor section for the loptop monitor you can put
Option "ignore" "true"

gary85 and tobySGD, thank you, but the problem is that I can't boot by live cd... If I type X -configure it gives me a "1777" error and if I type mkdir /mnt/dslinux and the other commands I get more strange errors...
Now, assuming that I have the access to the slackware linux rescue command line (from the installation cd) and to Damn Small linux live cd and there's a slackware-based distro installed on the laptop, how can I type those commands? (yeah, I know, it's a bit pathetic...)

Ok, I got an idea: I'll install slackware 13.37 but before "startx" I'll type X -configure and, if the external screen doesn't work I'll type all the stuff indicated by gary185. I'll post the results soon...

remember that from the rescue cd lots of the things you will need to do as root
i think 1777 is about permissions
most rescue cds root password is blank