Masked intruders forced their way into the Silver Spring home of a U.S. senator's daughter yesterday morning, startling a nanny who ran outside with the lawmaker's 2-year-old granddaughter and left his youngest grandson behind. A Montgomery County police SWAT team later found the baby safe in his crib. Police think the incident was a burglary gone awry because the intruders apparently didn't realize the house was occupied. The burglars approached the red-brick house on the 2400 block of Hayden Drive in Forest Glen about 9:30 a.m., police said. After hearing suspicious noises outside, the 42-year-old nanny opened the door. "When...