I have been using Avast 5 Pro for several months without any problems. Today the only way I can get to any website is to turn off the Web Shield. Since I have a free key and a pro license I have uninstalled Pro and installed Free and have the same results with both. I have not made any changes to either Avast or my OS (Windows 7 Pro). Windows firewalls are off and Avast is the only AV installed.
Cause for apparent Web Shield blocking internet connection, http://forum.avast.com/index.php?topic=57443.0.
I have set both TEMP and TMP to C:\Temp, I ensured that C:\Temp exists and everyone has full privileges, and I checked the registry to ensure that both variables are correctly set. I point both to a single folder to make it easy to delete the unnecessary files on a regular basis (I abhor having to dig into both my profile and the system directory just to delete temp files). As stated in my original post, I have changed nothing in either Avast or the OS and this problem just started today.