I was trying to figure out almost the same issue her for a Ubuntu 12.04 client which should run 24/7 without any blank or black screen. Maybe my way to fix things can help you, too:

First of all, I changed a line in /etc/default/grub, in order to switch off power management at all.

Old:

Code:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force"

New:

Code:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=off"

After a reboot, the terminal command

Code:
dmesg | grep -i ACPI

informed me that ACPI has been disabled.

Then I created a new file xset_off.sh in my home directory. Its content is

Code:
!#/bin/bash
exec xset -dpms s 0 0 s noblank s noexpose s off

(Don’t forget to make this file executable with

Code:
chmod +x ~/xset_off.sh

.)

In order to have this script run everytime when your X window environment is launched, you can either add it to your autostart objects in the GUI desktop. Or you create a new file ~/.config/autostart/xset_off.sh.desktop.

Mine has the following content (autogenerated by the GUI desktop):

Code:
[Desktop Entry]
Type=Application
Exec=/home/XXXXXXXX/xset_off.sh
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
Name[de_DE]=xset off
Name=xset off
Comment[de_DE]=Bildschirmschoner aus
Comment=Screen Saver Off

The next time when you have booted your system, a simple check of the xset parameters with

Code:
xset q

should inform you that both Screen Saver and DPMS have successfully been switched off.