Hi.
Is there a way to hide this popping window, which is quite high sometimes. ???
Thanks
Newcomer from Québec, Canada
Not much info but I guessing you have been tweaking the settings without knowing what the effect will be (avast help file) and enabled the ‘Show detailed info on performed action,’ which is disabled by default.
Standard Shield, Customize, Advanced, Show detailed info on performed action.
http://img.photobucket.com/albums/v325/for-dwr/ShowDetailedAction.jpg
http://img.photobucket.com/albums/v325/for-dwr/showdetailedweb.jpg
As you can see there are other shields that contain this option so you will need to ensure they are unchecked also to correct any that you enabled.
Welcome to the forums, Pagaie. 
Please let us know if David’s suggestion helps you. It should stop the pop-up window. Avast default settings are best as the are when installed for new users.
Please come back often, learn more, and maybe help others. 