Mountain View, Calif.--Larry Mueller, the CEO of troubled b-to-b e-procurement software developer Ariba Inc., has resigned after three months on the job. The company's board tapped chairman and co-founder Keith Krach to replace him as interim CEO. Krach ceded the CEO title to Mueller, formerly president-COO, in April. Ariba is seeking a permanent replacement to take the CEO job. Separately, Ariba posted a $273.5 million dollar third-quarter 2001 loss, versus a loss of $317.1 million in the year-earlier period. Some industry watchers are speculating that a bigger, healthier competitor-for example, Oracle Corp.-could soon snap up Ariba. Meanwhile, Ariba rival Commerce One Inc. recently secured a much-needed $225 million investment from SAP AG. Commerce One has had its own top management reshuffle recently. The Pleasanton, Calif.-based company's president, Robert Kimmitt, left to join AOL Time Warner Inc. as exec VP-global strategy and policy. COO and Vice Chairman Dennis H. Jones, who joined Commerce One in April after a stint as CEO of Accel-KKR Internet Co, replaced him.