Every time I hit a brightness key on my laptop's keyboard, it adjusts the brightness by three steps instead of one. How can I fix it so that it only adjusts one step at a time?

I am using an Acer Aspire D250 with the newest firmware. It was working better when I was using Ubuntu 10.10 with older firmware (although the scale was off).

Any tips on debugging this would be appreciated.

Edit: My graphics:

00:02.0 VGA compatible controller: Intel Corporation Mobile 945GME Express Integrated Graphics Controller (rev 03)

/sys/class/backlight$ ls
acpi_video0  intel_backlight