Have you installed any other security software on this machine now or in the past? If in the past, how did you uninstall it (including AIS)?
What version of AIS do you have installed now?
I would try again an uninstall and clean install of AIS:
1. Save a copy of Avast and save it to your HDD:
Avast Internet Security: http://files.avast.com/iavs5/avast_internet_security_setup.exe
2. Download the Avast Uninstall Utility http://www.avast.com/uninstall-utility
and save it to your HDD.
3. Disconnect from the Internet at this time.
4. Go into Safe Mode
(hit F8 repeatedly) and run the Avast Uninstall Tool. Uninstall ALL previous versions and products of Avast you had on this machine.
7. Install the newest version of Avast and reboot
8. Get Internet access and add the license key for AIS online.
9. Update the Avast definitions.
Also check for malware on your machine with both Avast and Malwarebytes Antimalware (MBAM) http://www.malwarebytes.org/
to make sure we are not dealing with another issue. Thank you.