Modem/Router and Internet problem?

A little background first. I have 2 computers - a customized PC running XP and a Compaq Presario V6608AU laptop running Vista Home OEM that the manufacturers provided. My modem is a StarCom UT300R2U router. My PC has an original KIS 2008, while I was using the free version of avast! anti-virus on my laptop. A few days ago my pals told me that they were facing problems with avast! as it was leading to a BSoD, which wasn't going away even in safe mode, and thus had to format their PCs. As a result I immediately removed avast!, but continued browsing the internet without it. However a couple of days ago, I found that my browser (which is chrome by the way) reported broken link for almost all the sites that I was trying to access (youtube, gamespot, metacafe, etc). So I installed a trial version of KIS 2008, and it detected a virus in my hosts file, and thus deleted it. However, the broken link problem still persisted with some of the sites. As a result I changed my connection type from 1483 Bridged LLC to PPPoE LLC. The broken link problem with most sites disappeared, but not with all. Moreover one site may be accessible one day and the another may not, but the very net day the one that was accessible will report a broken link, and the inaccessible site will become accessible. On top of this my modem hangs up (as in freezes up completely) within 15 - 30 min. However, a restart gets it up and running again. I scanned with KIS 2008 again, but it reported no viruses. PLEASE HELP.