Tennis Player Serena Abuses Line Judge

What is that all about? From what I've heard, after being called for a foot fault, Serena Williams approached the line judge and threatened her to stuff the tennis ball down the woman's throat while shooking her racket at the woman. From the way I see it, the judge made the right decision to disqualify Serena Williams from the semi final game which makes the opponent Kim Cligsters go straight to the final.