Did bob3160's suggestion work? If not, open C:\program files\alwil software\avast4\data. In the right panel open, with notepad,avast4.ini. Scroll down to the vrdb section. Is there a line Mergeicons=1 ? If there is change the 1 to a 0. Save the file. A reboot may be needed.
Or just copy and paste the vrdb section here.
Welcome to the forums
HTH
edited to correct spelling