Jennifer Aniston has hired a team of security guards after discovering someone on the set of her new movie has been stealing her underwear and selling it on eBay.The sexy star, filming 'The Break Up' with heartthrob Vince Vaughn, was horrified after finding the pervert had broken into her trailer and made off with her bras and knickers.The frilly items later appeared on the internet auction site.The screen beauty's private movie quarters are now being guarded round-the-clock.But despite her on-set problems, Jennifer marked the imminent end of filming the movie by throwing a sunset dinner cruise for cast and crew.The actress splashed out on the luxury boat party on Chicago's Lake Michigan.A source revealed: "Jen was in a giddy mood. When she arrived she kicked off her heels and ran up the gangplank!"
