In addition to the above suggestion, I also suggest the following:
You are also using an outdated (old) version of Avast. Try updating to the current version of Avast, which is 6.0.1125:
1. Save a copy of Avast for the product you need (if not already on your machine) and save it to your HDD:
http://www.avast.com/download-software2. Download the Avast Uninstall Utility
http://files.avast.com/files/eng/aswclear6.exe and save it to your HDD.
3. Disconnect from the Internet at this time.
4. Go to Control Panel and uninstall Avast through Add/Remove Programs if possible and reboot.
5. If Step 4 fails, boot into
Safe Mode (hit F8 repeatedly) and run the Avast Uninstall Tool.
6.
Reboot.
7. Install the newest version of Avast and
reboot.
8. Get Internet access and register your copy or add the license key for Free, Pro, or AIS.
9. Update the Avast definitions.
See if an updated version of Avast fixes your problem. Thank you.