Just to add on this.. My CIS will notify me of the same alert (nbnname port 137) also every time I boot up. This port block usually happens on my XP systems when running through networks. I found some interesting information on the subject of this port, along with 138, and 139, which according to the author of the articles I came across, Microsoft uses these ports for "the transport of their existing NetBIOS protocol over IP-based LAN and WAN networks. The horrors of insecurity resulting from Microsoft's exposure of their NetBIOS protocol to the Internet are legendary."
From my network configurations, this makes sense, and I prefer to block these ports, only because I do not share anything to or with any pc's, or phones, or pads, etc.. which connect to the network.. I simply block the port access upon each boot & I do NOT choose the remember my answer tab in the event I would actually like to share a file or printer with another device connected to the network.
Thats my 2 cents on the issue..
Related Article: http://www.grc.com/port_137.htm