I have a few friends who have recently been having issues with these tuners and Nortons firewall. Its an old topic but I couldnt find a thread on how to fix it in N360 specifically. Figured I would throw this out in case anyone needs it.

Here is what I did in Norton 360 and it solved the issue.

This procedure requires that you know which network connection you tuner is set as. To find this out open the control Panel and click on Network and Sharing Center. On the next screen click on Change adapter settings. Your digital cable tuner(s) should be listed under a local area connection(s.) Remember which ones they are using.

1. Open Norton 360.
2. Click the "Settings" header (top right.)
3. Click "My Network".
4. On the Network Security Map line click "Configure[+]"
5. Click initialize or okey when pop up appears

On the next screen there will be a drop down box on the left with your network connections listed. These tuners are Local Area Connection 2 and Local Area Connection 3.

6. Use the drop down menu to select your tuner.
7. Under Network Details click "[Edit]."
8. The Edit Network Details box opens. Next to trust level click "[Edit]."
9. On the next screen I changed them to "Full Trust"
10. Select okay and okay again.
11. Go back to step 6 if you have more than one tuner.

Hope it helps someone.