Odyssey Warns of Weak Quarter, CEO Quits  CHICAGO (Reuters) - Odyssey Healthcare Inc.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=ODSY.O target=/stocks/quickinfo/fullquote"&gt;ODSY.O&lt;/A&gt; on  Monday warned of an earnings shortfall, announced the  resignation of its chief executive and said it was the subject  of a Justice Department probe, sending shares of the hospice  care provider plummeting 42 percent.