Outbound traffic message upon startup

Good day. I'm running Norton 360 on Windows 7. I use Firefox. I've noticed when I go to save a web page I get the "outbound traffic detected" message with the suggestion to run Norton Power Eraser. Having done this a few times with no issues I have concluded that Norton always does this when I download a web page so I don't worry about it.

Recently, however, I receive this message right after starting up my computer. I have run the PWE with no issues, yet I still get the message once the computer has booted up. This has only been happening for the past week or so. Any thoughts or suggestions as to what this means or what I should do about it?

Thank you.