New Twist on "This Page Cannot be Displayed"

Ok, here's the deal folks:
I recently moved into a new apartment with some buddies. Upon first arriving we got the net hooked up and everything was fine. About two weeks later, however, we installed a router to split the connection between all 3 of our computers. Now my computer, and ONLY my computer, recieves the "this page cannot be displayed" error when accessing random sites. Now I've seen this problem addressed in many other threads all over the web and have tried almost every possible solution out there. Unfortunately my situation seems to be a little different then the rest. First, the sites I can't access are not all secure sites (and for that matter, I dont have any problem accessing most secure sites, like my banking account for example). Second, the problem persists regardless of which browser I use. I've tried Mozilla, Firefox, Opera, Netscape, and IE. Third, all of the websites that are blocked on my computer can be accessed easily from the other 2 computers in my house with no problem. Even if I change the port that my ethernet cable is hooked up to on the router, I still have the same problem. Also, we all run the most updated SP of Windows XP professional. Im at my wit's end here everyone, could someone kindly suggest an alternate solution?