NVIDIA driver and DPMS: backlight never switches off

Despite having configured DPMS according to all the docs I could find,
whilst my laptop screen will blank after a while the backlight never
switches off. Any suggestions?

Laptop: Dell Inspiron 8200

Graphics card: NVIDIA GeForce4 440 Go

Kernel and driver details:

        $ uname -r
        2.6.13-1.1532_FC4
        
        $ rpm -qa | grep -i nvidia | sort
        kernel-module-nvidia-2.6.13-1.1532_FC4-1.0.7676-0.lvn.2.4
        nvidia-glx-1.0.7676-0.lvn.3.4

Xorg log says DPMS is loaded and enabled:

        $ sudo grep -i dpms /var/log/Xorg.0.log
        (II) Loading extension DPMS
        (**) Option "dpms" "true"
        (**) NVIDIA(0): DPMS enabled

And xset seems to confirm that DPMS is enabled and the times for
standby, suspend, and off set in xscreensaver are picked up:

        $ xset -q
        [snip]
        DPMS (Energy Star):
          Standby: 1800    Suspend: 2700    Off: 3600
          DPMS is Enabled
          Monitor is On
        [snip]

Also,

        $ sudo xset dpms force [standby|suspend|off]

doesn't work either.

This *used* to work a couple of Fedora Cores and NVIDIA drivers ago.
However, I cannot remember when it stopped working (although it was a
while ago). I've been searching on the NVIDIA forums and through the
NVIDIA readme, and I can't seem to find anything. It'd be nice to get
this working again --- I often leave my laptop on overnight and I'm
beginning to get afraid that the screen will burn out at this rate.

Best, Darren

-- 
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D. D. Brierton            darren@xxxxxxxxxxx          www.dzr-web.com
       Trying is the first step towards failure (Homer Simpson)
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