When you help restore an item i.e a Jellysac Mound, you can sucessfully fill all the materials needed and collaborate with all the amount of work, but when the restoration process finishes the screen showing the progress just stays there and the sounds made by the action (digging, construction) keeps going and going until you leave the street.
Even if you close the restoration window the sound keeps going, altough the project is completed.
Win 7, Chrome.