Laptop screen brightness fading in and out

[Dave M G]

Ubuntu Users,

My laptop is running Xubuntu 8.10.

Since upgrading, when on battery power, the screen brightness fades in 
and out. It goes from mildly dark to really dark and back again. The 
change is slow, so that the gradual change is almost imperceptible. But 
there's no question that at times the screen brightness is easy to read, 
and sometimes very difficult.

The hardware brightness controls on my laptop model have never been 
supported by Ubuntu, so I've never really bothered trying to find the 
right brightness level. But now, the way it is, it's a little annoying. 
I wouldn't mind so much it being as dark as it gets, because the battery 
life is better with a darker screen. But the fading in and out is 
distracting.

So far as I can tell, though, there are no settings for screen 
brightness on battery power. Is that because ordinarily it is assumed to 
be controlled by the hardware?

Is there anything I can do to at least stop the fading in and out, if 
not gain more control over my brightness settings?

Any advice would be much appreciated.

-- 
Dave M G