Blue Chips Fall as 3M Results Disappoint  NEW YORK (Reuters) - U.S. blue-chip stocks fell on Monday  as Dow component 3M Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MMM.N target=/stocks/quickinfo/fullquote"&gt;MMM.N&lt;/A&gt; posted results slightly below  Wall Street estimates and oil prices held near \$55 a barrel.