Any word from the developers as to whether they're aware of this thread and issues with windows 10 build 10547?
Have you tried doing a repair of Avast
Program and Features > select Avast > then select Repair. When the repair is finished, reboot your computer.
See if that solves your problem.
Well 5th time lucky at installing Avast Free on build 10547 and it is all working, not sure why but these are the steps i used this time.
1. Closed Comodo firewall
2. Change the Avast default install folder to Avast2015
3. Cancelled the quick scan after installation
4. Closed down the PC from the Start Menu
5. Restarted
After the above all seems to be running normal, maybe it was Comodo, but that has never been an issue before, so i am a happy Avast user again.