Share experience to use. 
I use avast! version 5 and upgrade to 6 have problem in password protect avast feature it can’t remember password was reset it self.
Today i testing uninstall by uninstaller tool in windows safe mode (windows 7) [ https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=730&nav=0,615#idt_02 ]
and clean all program , restart to normal mode and clean installation avast 6 final again.
Work Fine. Password Protection is working now
The upgrade online way i think have problem in program or buging in avast program to fail in some feature , clean uninstall and new installations is right way.
(Sorry , my english language not good)
Thank you.