Strange IP on boot up

when I turn on my computer and log onto the internet, I will get these messages in system log of muy NAV2008

 

Protecting your connection to a newly detected network on adapter "NVIDIA nForce Networking Controller" (IP address: 192.168.1.64).

 

then within 45-60 seconds the following message

 

IP address 192.168.1.64 has disappeared and is no longer being protected.

 

then a few seconds later  I'll get my IP address from my ISP

 

what does this mean?