FW (NetDefense) says I have repeated port scanning attempts

My firewall program-Netdefense, part of SystemSuite 8 keeps warning me while online of repeated attempts to do port scans. When the warning flashes it is impossible to change web pages the browser locks until the warning is opened and then closed. It was so bad on my wife's puter that I had to change security systems with a new FW. Now it's been getting worse on mine.
I have WinXP Pro W SP2. The security report says the remote host is 192.168.1.254 , which is an Internet registry company named ARIN.net. They say they only register addresses and are not scanning my puter. Is there anything I can do to stop this or find who's responsible? Any help would be appreciated

Hi Dawg, It looks kike you may have been born about the time I got married. No one has responded so I will offer my solution. But first I want to complain that Parrilo did not make his sit compatable with my browser| https://www.grc.com/x/ne.dll?bh0bkyd2 Go to this site, it is Stev Gibson's Shields Up the follow the instructions. This will make your computer completly invisable to the internet. Good luck. D.D.