What do you mean by “I am using Avast! free antivirus from 2010 and not faceing this problem untill 2015 version”. Have you tried doing a repair of avast via add/remove? Did you use the correct method
Uninstalling avast via add/remove
Using the avast uninstaller utility
Using the antivirus removal tool from your previous antivirus
Reinstalling avast free again and doing a manual reboot once it has done a quick start up scan.