Network Security Map issues

Hi, this is my first time on the forum and will do my best to describe my issues.

 

I recently purchased Norton Internet Security for my PC which is running XP sp3. After a few days of running I have noticed when I go into network security map there are more than 1 comupter connected to my network. Sometimes 4. I have the wireless feature disconected on my router/modem combo and was curious to know why. I have on 1 computer connected to the network.

 

The other devices on the network have different physical addresses and IP addresses. They come and go from time to time and change my network name saved in NSM. I have also noticed that my ip address sometimes changes. When I click on edit device name, under property/value section, my IP and physical addresses are different from the ones on the main NSM page.

 

Devices also show up in the Trust Control tab.

 

They always come up as NEW and some have manufactueres names some don't.

 

I have formatted my hard drive and have done a clean install as to remove any malicious files on my hard drive.

 

There are a lot of features with Norton Internet security and I would like to now how to best set it up to prevent  others from accessing my network.

 

Thanks.