Websites Work On And Off

Since thunder caused a brief shortage a week ago, I have been getting this error a lot:So when and how does this happen? Some of the time, all sites work perfectly. The rest of the time, about half the sites I try to visit yield this error. I might be browsing Website X for a while, and spontaneously, I start getting this blank screen error message for every page on that site. Unreachable sites usually start working within ~10 minutes though. Some sites always work (e.g. Reddit and Google, but not always the images in Google Images).If I try this on my laptop, using the same network cable, everything works perfectly. My computer is the only one in the house that has this error, for some reason.I have tried "ipconfig /flushdns", "ipconfig /renew", Google's DNS and OpenDNS, the "repair connection" thingie in Windows XP, restarting the server (well, my dad has), opening sites in Internet Explorer (I usually use Firefox) and unplugging/replugging my router.I haven't had any success although I have twice been tricked into believing that I've solved the problem, since all sites have randomly decided to work for a few minutes (non-reproducable of course).