On August 17, 2007, Dell Inc. announced that after an internal investigation into its accounting practices it would restate and reduce earnings from 2003 through to the first quarter of 2007 by a total amount of between $50 million and $150 million, or 2 cents to 7 cents per share. The investigation, begun in November 2006, resulted from concerns raised by the U.S. Securities and Exchange Commission over some documents and information that Dell Inc. had submitted. It was alleged that Dell had not disclosed large exclusivity payments received from Intel for agreeing not to buy processors from rival manufacturer AMD. In 2010 Dell finally paid $100 million to settle the SEC's charges of fraud. Michael Dell and other executives also paid penalties and suffered other sanctions, without admitting or denying the charges.

What department did Dell launch an internal investigation on?