the manufacturers who told me the best thing to do would be a system reset,
if that means any factory installed antivirus is also restored, this must be removed before installing avast

third party removal http://www.avast.com/faq.php?article=AVKB11#artTitle

then download and install avast … and insert your license

avast FAQ http://www.avast.com/faq.php

how to do videos http://www.avast.com/faq.php?q=video#searchForm