An unhappy iTunes online music store customer is suing Apple Computer, alleging the company broke antitrust laws by allowing iTunes to work only with its own music player, the iPod, freezing out competitors, court filings showed. Apple, which opened its online music store in April 2003 after introducing the iPod in October 2001, uses technology to ensure each digital song bought from its store only plays on the iPod. The suit was filed on Monday in the U.S. District Court in San Jose, Calif. One antitrust expert called it a long shot, but Californian Thomas Slattery is hoping for unspecified damages for being "forced" to buy an iPod, one of the most successful electronics products in years. The key to such a lawsuit would be convincing a court that a single product brand like iTunes is a market in itself separate from the rest of the online music market, according to Ernest Gellhorn, an antitrust law professor at George Mason University.