DEERFIELD, Ill. Rein, a 26-year Walgreens veteran who built a reputation for quiet-spoken but determined leadership, effective people skills and competitive drive, expressed "great confidence in the company's future." But his abrupt departure comes in the wake of Walgreens' unsuccessful bid for Longs Drug Stores and in the midst of an alarming drop in consumer confidence amid Wall Street's financial meltdown. Rein, 56, also gave up his seat on Walgreens' board of directors, cutting all official ties with the nation's largest drug chain. The company named 62-year-old Alan McNally, the board's lead director, to serve as acting chairman and chief executive officer, and to help lead a nationwide search for Rein's successor. Undertaking that search will be a special committee of three board members. In addition to McNally, that committee includes William Foote, chairman of the governance committee, and James Skinner, chairman of the compensation committee.