Intrusion Detection

I am using NIS 2010 in conjunction with windows 7.  I have been getting frequent intrusion detection notifications.  The intrusion is identified as a portscan that matches an attack signature.  The address listed is my DNS server.  This happens on several different DNS servers.  Should I regard  this as an actual attack attempt? or do I have a problem with something else.  I connect via wireless to an access point at my work location.  Thanks in advance.

Message Edited by Richk on 12-27-2009 05:35 PM