All right, computer nerds, I've got an HP Pavilion zv6000 laptop that's supposed to be brighter when plugged in than when running off of its battery. Well once in a while, usually when I turn it completely off and then on again later, the brightness switches. It's brighter when it's not plugged in and then dims when you plug it in. I hate this setting and only through sheer luck and a lot of not-knowing-what-I'm-doing techniques (involving a lot of unplugging while shutting down and plugging in while off and then unplugging while on then shutting off etc etc etc) I can revert it back to its normal setting.
Can someone tell me what I can do to either prevent this from happening or fix it immediately when it does happen?