After the Bell-National Instruments Falls  NEW YORK (Reuters) - Shares of National Instruments Corp.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=NATI.O target=/stocks/quickinfo/fullquote"&gt;NATI.O&lt;/A&gt; fell over seven percent after the close of regular  trade on Monday after it cut its third-quarter earnings per  share and revenue outlook.