Jany, do things like the Windows Control Panel work correctly? Also, the Windows Help?
If not, it's probably an avast ScriptBlocker problem and the best way to solve it is to uninstall avast, reboot, reinstall avast.
There're simpler ways as well but they actually tend to be more consuming because they require you to know exactly what you're doing (manual editing of the registry etc).
Thanks
Vlk