It could very well be hardware related. One trick that I've seen is to create a new power profile, i.e. right click on the battery icon in the system tray. Sometimes this will refresh the power system. If that doesn't work, it could also be the battery. How old is the battery? Basically, I'm trying to rule everything out before we jump to conclusions about it being something like the motherboard, which as you know is basically the end of the laptop.