I've got the same problems.
Function setifaceUpdatePackages() has failed. Return Code is 0xC0000005, dwRes is C0000005
Now, as a programmer, I know that 0xC0000005 means Exception Violation, which means some code somewhere in the application is trying to access memory it doesn't own. This is a bug.
Additionally, Avast seems to be forcing activation of the Windows Internet Connection Sharing and Firewall service, even when the firewall is disabled. You see this by going into Network Connections and you'll see the "Internet Connection" icon. This shouldn't be happening, since i've disabled my firewall for a reason (I have a hardware firewall, I don't want a software one).
The ICS icon only appears when Avast tries to update, and then will not go away after that without a reboot, but then as soon as Avast tries to access it again, it's back again.
There is a problem here, and lots of people are seeing it. This didn't happen prior to the 731 update. Everything worked fine.