Office Depot Chairman, CEO Nelson Resigns  NEW YORK (Reuters) - Office Depot Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=ODP.N target=/stocks/quickinfo/fullquote"&gt;ODP.N&lt;/A&gt;, the No. 2  U.S. office supply chain, on Monday said Chairman and Chief  Executive Bruce Nelson resigned and a search for his successor  is under way.