I suggest an uninstall of Avast and
CLEAN install to fix your problems.
Please follow these instructions:Save a copy of newest version of Avast.Save the http://www.avast.com/uninstall-utility on your hard drive.
Disconnect from the Internet at this time.
Uninstall Avast through "Add/Remove Programs".
Boot into Safe Mode and run the Avast Uninstall Tool.
Reboot twice.
Clean your computer up.
Install the newest version of Avast and reboot twice.
Get Internet access and update Avast definitions.
Register your free copy or add the license key.
Reset your settings, if needed.
Run a scan (try a Full System Scan initially to check for malware).
Please let us know if you have any further questions or problems after completing the above or questions prior to completing the above mentioned steps. Thank you.