Have a look at what Norton may be doing as far as your hard drive is concerned. Sometimes the only way to test if a particular program is a problem, if you cannot disable it, is to uninstall the program for testing purposes, and then after testing to reinstall it.
Defragmentation [ Edited ]
https://community.norton.com/t5/Norton-360/Defragmentation/td-p/609654
Does Norton Defrag my computer?
https://community.norton.com/t5/Norton-360/Does-Norton-Defrag-my-computer/td-p/901935