Wonder Bread Baker Stock Drops 25 Percent  NEW YORK (Reuters) -  Interstate Bakeries Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=IBC.N target=/stocks/quickinfo/fullquote"&gt;IBC.N&lt;/A&gt;,  maker of Wonder bread and Hostess Twinkies, on Monday said it  hired a turnaround firm, delayed filing its annual report and  outlined possible credit concerns, sending its shares tumbling  more than 25 percent.