Port 554 opened by NIS 2011

Hello.  I saw the other threads here about people who ran GRC Shields Up and found that port 554 was open.

 

When I was using Windows Firewall, I was completely Stealth according to GRC's site.  I decided to install Norton Internet Security 2011, thinking this would make me more secure.  I reran the GRC test and it showed my port 554 was now open.

 

Why does the Norton firewall open up this port?  And more importanty, how can I Stealth this port?  I did not understand the answers on this forum instructing to shut off Windows Media Player.

 

I am starting to think maybe I would be better off going back to the Windows Firewall.  :(