This is Mike from the Norton Authorized Support Team responding to your post.
The first question I have for you is what version of Norton Internet Security do you have installed? Please reply back and let me know.
I will assume that you are using the 2008 version, and I would like to give you the steps to check your settings to see if by chance you may have missed something. Please make sure that your internet connection is working correctly before proceeding.
1. Launch Norton Internet Security's main window from the Start menu or by double-clicking on the Norton protection Center icon in the system tray.
2. Click on the "Norton internet Security" tab at the top of the window. Next, click on the arrow next to "Settings" to expand the options.
3. Click on "Auto Protect" and then click the "Configure" button. Make sure that there is a check in each of the boxes. Click the "Apply" button at the bottom of the window and then click the "OK" button. You should now be back in the main Norton Internet Security window.
Now, I would like you to check your settings for LiveUpdate.
1. To do so, click on "Settings" and then click on "Automatic LiveUpdate," and then click the 'Configure" button. make sure there is a check in the box next to "Turn on Automatic LiveUpdate." The other box that says "Notify Me When Updates are available" is a matter of choice. Lastly, make sure there is a check in the box that says 'Run Quick scan...." Click the "Apply" button and then click the "OK" button. You can now close the Norton Internet Security window.
If you receive any error messages about LiveUpdate not being able to connect, we have another solution called the "Intelligent Updater. This will download a self-contained update program that you run. Please click on the following link to download an run the tool:
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Please try these steps and reply back and let me know if this resolves your issue. Please also remember to clarify the version of Norton internet Security you are using.