Intrusion Attempt

I use Norton & it's never happened to me, Pitter.

Is there any more info about the intrusion in the warning pop-up? A good thing to do might be to consult Norton's documentation ... an answer might lurk in the application's user manual. How do you have Norton configured? What sort of internet connection do you have? Is your machine on a network? If so does it have standalone internet access or is it the Internet Connection Sharing gateway machine or is it a client? Do you use any sort of P2P filesharing?

The message the Norton pop-up leads to is:

Security Rule: Default block netspy trojan horse

I have a dial up connection and I'm not on a network. I'm not sure how Norton is configured. I just purchased and downloaded it.

Might be more helpful to know the entire message, but I'm gonna say odds are, since it occurs right after boot-up, you use dial-up, and you're not on a network, that its a false alarm. See This

Wouldn't hurt to do a full system virus scan, but I doubt you've got anything there to worry about.