I was having some problems with this on Intrepid but hoped that the upgrade to Jaunty would help - but it hasn't.
On my nx9420 I have LCD brightness buttons on the top of the keyboard. The display is dim and doesn't change despite being on AC power or the buttons being used.
Pressing the buttons does trigger the screen brightness applet in the top right corner of the screen but the screen's brightness doesn't change. Not sure how to troubleshoot this issue so would appreciate some guidance from someone who knows more.
Thanks in advance.