Just checked On Line Scanner. Looks like Script Blocking is off. I tried to turn it on and asks if want to save your changes-pressed yes and then no. I get error saying operation could not be completed. It is also grayed out. Also Script blocking icon in settings is grayed out. Any ideas? Thanks.
Are you using avast 4 Pro?
Which is your browser?
Which is your Windows? 98, Me, XP, Vista?
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).