The Associated Press reports that PayPal Inc. has filed suit against Bank One Corp., alleging the bank's online bill payment system infringes on its patent for processing payments over the Internet. Meanwhile, First USA Bank filed a complaint against PayPal a year ago alleging patent infringement, according to eBay stock filings with the SEC. In a related story, this week, Citigroup announced it was ceasing operations of its online payment service called c2it.