Try turning off your firewall just long enough to try the updates as i had a problem like this a while ago. If i needed to update my pc i had to disable NIS2003 to get them. I think its unlikely that this is happening to you but its worth a try. Also, have you done the usual spyware and virus scans? You could try cleaning your browser too. Ad-Aware Spybot seach and destroy Spywareblaster