An autopsy of "Happy Days" star Erin Moran showed that she probably died of cancer, according to the Harrison County Sheriff's Office and the county coroner.<br /> A statement released by authorities Monday said that an autopsy found that Moran "likely succumbed to complications of stage 4 cancer."<br /><br /> The Sheriff also said "standard toxicology tests were performed and the results are pending, however no illegal narcotics were found at the residence."<br /> The actress played Joanie Cunningham for most of the sitcom's decade-long run in the 1970s and 1980
