Windows 7: Avast Web And Mail Shields

I just installed Avast Free AV, considering it as a replacement for Outpost Security Suite, which I have been having problems with. However, once installed, my browser (Opera) was not able to display web pages, until I disabled the Web Shield. While typing this, I also found that the same happened with the Mail Shield until disabling it.

It seems odd that this would happen with the default settings immediately after installation, and I considering uninstalling it, but wanted to see if anyone knows how to fix it first?

One question how did you remove outpost? May be some leftover of outpost is causing the problem. I have seen many people reporting this problem in avast forum when they cannot connect to internet without disabiling webshield. a clean reinstallation seems to solve the problem. I suggest first remove avast by the procedure given by the vendor then again run outpost uninstaller to remove any leftover of outpost then download a fresh copy of avast and reinstall.

How do I uninstall Outpost manually?
avast! Uninstall Utility