Stocks Seen Flat as Nortel and Oil Weigh  NEW YORK (Reuters) - U.S. stocks were set to open near  unchanged on Thursday after a warning from technology  bellwether Nortel Networks Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=NT.N target=/stocks/quickinfo/fullquote"&gt;NT.N&lt;/A&gt; dimmed hopes, while  stubbornly high oil prices also weighed on sentiment.