Spam about "Default Block Windows File Sharing"


I'm running Norton Internet Security 2012 on windows XP
This morning when starting up I got a windows sytem alert that "Noton was disabled". The Norton log showed:

High
Download Avdisor turned off.
2012-03-27 10:08:11


Since then, no mater how many times the computers and router are restarted, every every two or three seconds, I get this message in the log:


Info
Rule "Default Block Windows File Sharing" blocked (192.168.1.35, Port (139) ).  Inbound TCP connection. ",Detected,No Action Required,
2012-03-27 12:54:08

Rule "Default Block Windows File Sharing" blocked (192.168.1.35, Port (139) ).
Inbound TCP connection.
Local address, service is (UTOPIA (192.168.1.36), Port (139) ).
Remote address, service is (192.168.1.35, Port (49154) ).
Process name is "System".




More information:

192.168.1.36 is a windowsXp machine
192.168.1.35 is an imac
both are behind a comtrend router.


So what's going on? How do I stop it?