|I wouldn't necessarily rely on Norton to find stuff. |
Do you have a broadband, always on connection? Do you shut down your computer when not in use?
If the above apply then Windows and/or othr programs may be downloading updates when you do turn on the computer.
Or your computer may be a bot for spam or whatever. You can install a meter to see what volume of traffic is going in and out on your connection. That type of malware is hard to detect.
My thought is that your problem must be internet related because it goes away when to close down the internet connection.
You could try booting to safe mode (F8 at start up) with internet and see if you still have the same issue.