I have experianced the exact same problem, FF and IE stops displaying webpages but everything else works (mail, torrent, RSS etc etc). Both times was after an update and the only way I got FF and IE to work was to use the system restore feature. Vista64 said that the (this might be the wrong name for it I use Vista in swedish) Data Execution Protection something had blocked FF and IE due to something....I tried finding info on this but appart from a thread in a swedish forum I could not find any other information about this problem. As now I dont dare upgrading or patching Vista att all due to the fact that the last two updates has led to IE and FF refusing to display webpages.