Even as the doors open this month on a new $43-million building to house the inaugural nursing class at Charles Drew University of Medicine and Science, the university's interim president warned that the long-struggling institution is already in danger of losing the facility. Beginning in September, the university will be forced to begin burning through a reserve fund to make loan payments, Dr. Keith Norris said in an interview with The Times. Without assistance from a government agency, foundation, charity or some other organization, Norris said, within six months the school could run out of money to pay for the 120-student nursing school building.