I can only open facebook when I turn off Avast. When Avast is turned on, no messages are displayed by Avast on a blocked web site but my page is not loading
That shouldn’t be happening.
Try a repair:
Start > Control Panel > Programs & Features > Uninstall a Program > select Avast and click " Uninstall/Change ". Choose " Repair " and “Continue”.
Once the repair is completed, it is essential that you reboot even if it doesn’t tell you to.