I think that is a router/cable issue. my old dorms used to get something like this, it usually fixed itself or was accompanied by another DNS error. unfortunately i wont have much of a real answer here, all i know is DNS based errors is when your connection ether cannot reach the Domain Name Server, or has somehow gotten stuck on a particular address.
EDIT: if you can find your DNS ip code switch to or from 8.8.8.8<->8.8.8.4 sometimes that is known to work apparently (not an original answer...that is a google search result...)