I just did a full reinstall on a Dell Latitude laptop wt XP Pro, and all updates. And a new install of Avast 4.8 Home. If webshield is running, Explorer will not connect, but I can update Avast, or Malaware bytes. If I run diagnosis, it tells me there is no problems found. I have to disable Web Shield to get explorer to work.
Like all changes to programs, etc. including new/re installations, firewalls block, though it should be more gentlemanly and at least ask rather than block without notification.
What is your firewall ?
Does it allow ashWebSv.exe internet access ?
If it does delete the entry for it and reconnect to the internet, this should force the firewall to ask permission again.
Standard Mircosoft on machine. I have never hard this problem till it did the up date on the 17th. I made no other changes. IE just give me a can not connect error.