Boot scan not working

Hi

I have avast free and when I try to do a boot scan, the screen will stay black and shows nothing, but if I press the esc button, it will get the laptop to start up normally. Does anyone know what is wrong?

Stephen

any other security programs installed?
have all previous used AV been uninstalled?
did you use the vendors removal tool to clear any leftover files that may conflict? http://singularlabs.com/uninstallers/security-software/

try a new clean install

run this from safe mode, and remove all used avast version http://www.avast.com/en-no/uninstall-utility

download and install again http://www.avast.com/en-no/download-software