Ghosts in the machine

Every now and then, on my Powerbook, I'll suddenly be unable to connect to a website I browse regularly. Right now it's I just get timeouts. No such problem if I use my Windows computer, hooked up to the same cable modem. A while back I couldn't access my own website.
Very strange--a DNS server gnome of some sort?
The other problem with Powerbooks--they heat up like a frying pan when you're working. I had to buy a one of those lap-tables because I was close to getting third-degree burns on my legs. It wouldn't be a sexy improvement, but laptop manufacturers need to spend some time developing laptops that can be used on, well, laptops.