I have no problem with any of those with web shield enabled and outpost pro firewall.
What OS are you running on your laptop ?
What browser are you using (I use firefox as default) have you tried an alternate ?
I'm at a loss as to what might be interacting to cause this as the web shield shouldn't block.
Try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this, I doubt this will resolve it, but it is an easy option to try first.
If that doesn't work try, uninstall, reboot, install, reboot.
It would probably be best to download the latest version of avast and save it to your HDD, somewhere you can find it again. Use that when you reinstall.