Singer Diana Ross, 58, voluntarily entered the Promises drug and alcohol rehabilitation center in Malibu's Santa Monica Mountains sometime last week, in anticipation of her international summer tour which is scheduled to begin in Germany on July 26, it was reported Thursday. She intends "to clear up some personal issues," according to a publicist's statement given to the Associated Press. "She wants to be in great shape because she is someone who feels a sense of responsibility to her family and her fans," the statement said. No further details were reported, though publicist Paul Block did say that the tour is expected to commence on schedule. Promises, which on its Web site describes itself as "an unrivaled setting for the recovery from drug addiction and alcoholism to begin," was also where "The Sum of All Fears" star Ben Affleck, 29, arranged to be checked in last August when he felt his life was spinning out of control. As PEOPLE reported at the time, former Promises patient Charlie Sheen, then 35, helped Affleck set up a room there and then drove Affleck to the $33,850-a-month clifftop retreat, where comedian Paula Poundstone was also in residence. "Ben is a self-aware and smart man who has decided that a fuller life awaits him without alcohol," his publicist said in a statement five days later. "He is committed to traveling a healthier road with the support of his family, friends and fans."