Power cable causing lag...

The strangest thing keeps happening to me. I'm running an HP notebook (dv6000 family) and every time I plug the power cable in, my connection speed goes WAY down. I'm using an 802.11b router and my ping in most games hovers around 90, when I plug the laptop in, the ping fluctuates wildly, jumping between 90 and 1000 though usually staying between 300 and 600. Any ideas of why this could be?

It's very annoying to only be able to play games when it's been charged and I can unplug it.