Using any browser (Chrome and Bing), Norton Safe Search blocks everything I attempt to search, even known "safe sites" and shows "http s : / / dreel flagman <dot> net / metric / ? wid = 5 2 8 1 3 " as a malicious site.
[Edit: Removed hyperlink of a potentially malicious page to conform with the Participation Guidelines and Terms of Service]
If this is happening on different browsers, it looks like you may have picked up a PUP, a Possibly Unwanted Program. While they are annoying, they do not cause damage to your system. Some people actually want the 'Features' offered by these programs. They are usually downloaded alongside a legitimate download when you do not uncheck the option for the additional download.
Norton products concentrate on malware that can damage your system, that is why some PUPs are not detected.
After a full system scan with your 360, I would suggest a second opinion scan using the FREE version of Malwarebytes. You can find it here https://www.malwarebytes.com/premium/