Disable the AOS in your browser(s).
avast 8.0 did not have the AOS. If you are still using v8.0 you might want to update to v2014.
Download and save the avast uninstaller
Download and save your choice..FreeProAvast Internet SecurityPremier
Run uninstaller from above. You will be directed to reboot into safe mode click "yes".
Install choice from above. Use the "custom install" and untick "browser protection".
Reboot and either register or insert license.
Dell Inspiron, Win10x64, MalwareBytes Premium--HP Envy Win10x64, MalwareBytes Premium,--Both systems Avast Free v2015.10.3.2225, MalwareBytes Anti-Exploit Free, Super Anti-Spyware, Spyware Blaster, MCShield, Unchecky, Firefox (latest build) and, various browser security tools.
"Look before you leap!" Use online scanners before you click on any link.