I use the Opera browser which has a VPN built-in; it is called SurfEasy VPN. After installing Avast Internet Security the VPN was no longer able to connect to the SurfEasy servers. I assumed it was because Avast has it's own VPN, so I disabled SecureLine VPN, but that made no difference. I started disabling each component of Avast, one at a time, until I found that the Webshield is causing the problem. When I turn it off, the SurfEasy VPN is able to connect normally. After the Webshield turns back on, the VPN is still connecting OK until I close the browser and then open a new session, at which point the VPN will not connect, again. Seems like a bug.