This is more of an FYI than a problem. I have a system running Windows XP SP3 with Zonealarm and Avast installed. I updated Avast from a previous version (I honestly don't recall how old, perhaps more than a year), and after installing the update, I could not load any webpages or access any online content.
Upon disabling the Avast provider, internet connections would act as normal, and upon re-enabling them the connections would die.
I found out that it's a problem with Zonealarm, HOWEVER, I had to "Allow" all of the Avast services in Zonealarm as both "Access" and "Server" modes. Leaving the "Server" modes as "ask" would result in no internet functionality.
Hopefully this saves others the time of discovering it themselves...lol