Avast Premium Freezing my PC

Just bought Avast Premium but it causes my pc to crash after an hour or two. Nothing in the logs says something is failing. Is there anyway to get a refund?

Did you remove the existing antivirus before installing Avast? Do you have any other security software installed?

Request a refund- https://www.avast.com/faq.php?article=AVKB24#idt_0430

Links to instructions/tools to remove av’s > http://www.ache.nl

How to Successfully Install Avast http://goo.gl/VLXde