impossible to enable resident protection

[Umondel]

I found the resident protection on DISABLE.
When I switch to "enable", it doesn't work;

I haven't any Norton antivirus system

Any tip ?

[Lisandro]

Which is your Windows? 98, Me, XP?

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). You must be connected to the internet while repairing.

If this does not help, can you uninstall / boot / install / boot again?