Pondus
2
do you have any other security programs installed?
did you just install avast?
if so, did you remove your previous used AV according to vendors instructions / removal tool ?
General: Uninstalling a third-party antivirus software http://www.avast.com/en-eu/faq.php?article=AVKB11#artTitle
have you tried avast repair and reboot?
contolpanel > Ad/remove programs > avast > uninstall / Change > repair option