Issue with brightness control on battery power

Hi all,
I wanted to know if anyone ever had an issue like this. I have a dv2500t running Vista (clean install from the anytime upgrade disc). I've noticed that the Fn+F7, F8 to increase and decrease brightness only works when I'm plugged into the power and not when I'm running on battery. I can adjust the brightness in the Advanced power options and set the default brightness level when on battery power. When I pull the power cord out it defaults to this defined level. But then if I want to change it, it doesn't let me. I'm wondering if this is something that Vista does. I was running XP sometime back and never had this issue. It could also be that something crapped out in my computer at the same time I switched.

Any help would be nice. I'm running a bios version one below the latest one (I think F25 is the latest).

Thanks

 

It happens with me as well. Tried it out after reading your post.

 

Hmmm, mine works after just finishing a clean install from a windows anytime upgrade DVD.

Sorry I can't help but I have no idea, I haven't even installed any HP program.

 

Try to get the latest QLB from HP , it fixed this problem for me.

 

Ok, A re-installation of the QLB seems to have fixed the issue. Strangely, HP customer support told me that my motherboard is buggered up and I'll have to send the computer in for repair. Go figure!