New York cab drivers are often fodder for stand-up comedians, but to actor Danny Glover, they're anything but a laughing matter. Reuters reports that Glover has filed a formal complaint with the city's Taxi and Limousine Commission, saying cabbies routinely do not pick him up because he is black. ''It happens to countless people every single day,'' Glover, 52, said at a news conference. He added that drivers bypass black customers even if their vehicles are unoccupied and on duty. ''The fact that I am a celebrity, the fact that I am visible allows me to draw attention to the issue,'' said Glover, best known for the "Lethal Weapon" actions films. He has also portrayed South African leader Nelson Mandela in the 1987 cable TV film ''Mandela.'' Commission spokesman Allan Fromberg said the city's taxi regulator planned to investigate Glover's charges.