Hello,
today I've tried to update my avast to the version 8.0.1483 because the program asked me to do so. The update seemed to have gone well, then I was asked to restart the pc. I've done it but when I logged in I saw that avast was not active: the home page of the program tells me the pc is not protected and if I try to activate it, a message tells me that another program is trying to stop the activation. When I try to proceed, my pc stops working and I can't do anything but turn it off and restart. I also tried to uninstall, re-download and reinstall it, but everything happens again.
I think no other firewall is obstaculating avast: I have also malwarebytes and spybot installed, but they are passive and 'till now they didn't interfere with avast.
I thougth about a virus, so I scansioned my system with spybot and removed some stuff, but nothing has changed. I don't now if the problem is internal or external to the system, maybe something in the pc is damaged (a popup avast message is telling me that the subsistem AAVM has found an RPC error).