When I try to fix the the fire wall shield that is in the off mode I get a message that firewall shield is unreachable.
Which is your Windows? 98, Me, XP, Vista, 7?
Do you use any other antivirus in your computer?
Can you try to repair your installation?
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove. Then choose Repair function in the popup window (Repair).
If this does not help, can you uninstall / boot / install / boot again?