Whitney Houston, who ruled as pop music's queen until her majestic voice and regal image were ravaged by drug use, erratic behavior and a tumultuous marriage to singer Bobby Brown, has died. She was 48. Houston's publicist, Kristen Foster, said Saturday that the singer had died, but the cause and the location of her death were unknown. News of Houston's death came on the eve of music's biggest night — the Grammy Awards. It's a showcase where she once reigned, and her death was sure to case a heavy pall on Sunday's ceremony. Houston's longtime mentor Clive Davis was to hold his annual concert and dinner Saturday; it was unclear if it was going to go forward.