I've got a strange problem with my backlight - I can't adjust it, even though pressing the specific keys on my keyboard makes a window pop up, telling me the percentage of the light intensity. Under the root user it works just fine, but when I log on with my own user, I seem to have this problem.
I've got Slackware 13.1, 64 bits and I'm using KDE4.

Can anyone help?

Thanks

This is likely a permissions issue. Which version of KDE 4 do you use? In addition, do you have PolicyKit installed?

I use KDE 4.4.3 and I don't know if I have a policykit installed.

KDE 4.4.3 is very old, please update to a newer KDE, preferably 4.6. If you have concerns about KDE PIM compatibility, I believe KDE 4.4 PIM is still available. Your distributor will have more information. They will also have information on PolicyKit.

I thought just the simple FN + F5 or F6 would've done the trick....
Anyways, guess that's been solved now.

fn + f5/f6 is not for all laptops. I have a hp elitebook and mines are FN F9/F10.

Meanwhile I've uninstalled KDE and got back to ubuntu (I've tried installing Kubuntu, but I got an installation crash, but that's another topic)

Thanks for that Vinci. Hadn't realised. Thought it would be identical on all keyboards, irrespective of make/model.