Norton Internet Security blocks spybotsd_includes.exe Download

Earlier today I was trying to download manually Spybot-S&D 1.6.2 Detection updates© 2010-03-03 from http://www.safer-networking.org/en/download/index.html website. My Norton Internet Security 2004 alerted me as follows:
Attempted Intrusion "NMap Null Scan" against your machine was detected and blocked
Intruder: www.spybotupdates.biz(213.165.90.132)(http(80))
Risk Level: Medium
Protocol: TCP
Attacked IP: [my DHCP IP address]
Attacked Port: 2659
Intrusion detected and blocked. All communication with www.spybotupdates.biz(213.165.90.132) will be blocked for 30 minutes.

I discovered that the file downloaded spybotsd_includes.exe was much smaller than the expected 6MByte.
After 33 minutes I managed to download the correct file without any difficulty. I than ran it and updated my Spybot application.