Vlk instructions always work ;D
Maybe you didn´t have the 4.1.280 version at first time and the recent versions (4.1.268 and 4.1.278) were buggy about updates…
Everything is ok now… 
When you update the program you get the virus definitions updated too… At this time, try to use more the program update because they´re very frequently and avast! is becoming better and better… 