CPU usage shoots up when on AC power

[squil0]

I have a HP notebook running Kubuntu, and a couple of weeks ago I noticed the following problem: when I'm on AC power, CPU usage shoots up to enormous levels, with top showing some processes using 800%, 1000% CPU, there seems to be no upper boundary. However when I'm on battery power everything seems back to normal, computer works fine. For a while I thought BIOS upgrade would work, but it was fine for two or three weeks and now it's back. Any ideas what could be happening?

Thanks for any help, I have no idea what's going on...

[teaker1s]

while I don't know exactly why your computer is behaving this way- try issuing the command

top
it will show you the most demanding applications and give you a starting point to look for bug or config errors