Well perhaps it’s time to call in the avast! team then. I will report this thread to the mods. One final thought though but admittedly it is fishing in the dark, can you try disabling the rootkit scan on startup in avast!, restart the pc afterwards of course ? avast! → settings → troubleshooting

Reason i thought of this is because HackShield does use some rootkit type methods to fish for cheats. Most of these anti-cheat systems are like that though, i remember there were problems with VAC aswell when avast! first introduced the behavior shield.