3Com Posts Wider-Than-Expected Loss  CHICAGO (Reuters) - 3Com Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=COMS.O target=/stocks/quickinfo/fullquote"&gt;COMS.O&lt;/A&gt; on     Thursday posted  a wider-than-expected second-quarter loss, amid stiff  competition from Cisco Systems Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=CSCO.O target=/stocks/quickinfo/fullquote"&gt;CSCO.O&lt;/A&gt; and others in the  telecommunications networking market.