I do a Reset ->Erase All Content and Settings. Looks ok but somehow the Whatsapp setting remain (all other apps disappear). I reboot it, it disappears for a while and appear again but you can't open it. Is there something wrong? I am not using the Whatsapp, so not an issue, just feeling curious? Any easy way to solve it? Is there possibility of malware or anyway to remove it without reformatting etc?