LOS ANGELES (Reuters) - Matt Roberts, a founding member of Mississippi rock band 3 Doors Down, is leaving the group after nearly two decades due to health issues, the band said on Thursday. "3 Doors Down will always have a special place in my heart and it saddens me to take this time off ... But my health has to be my first priority," Roberts said on the band's official website. Roberts did not elaborate but the website said his problems stemmed from circulation issues exacerbated by the band's performance schedule, playing nearly 300 dates a year. ...