Mears the other question is, do you have any other computers or just the one?
If you have just the one then just ignore them like he said, probably a script kiddie, or someone else on your cable segment that has their file and printer sharing enabled to everyone.
However if you have more than 1 computer, can you see each other on the network and get to shared files? If NOT, then you need to go into the security settings and tell the "Firewall" that it is ok to receive packets from the IP addresses of your other computers. Since more than likely the internal network is setup at 192. something, the internet won't route those packets anywhere else.
The NetBios scan is part of TCP/IP often for File/Printer sharing. But not 100% of the time of course.