I'd suspect video drivers as well. Boot into safe mode, uninstall the video drivers, reboot and log in as normal, and install new video drivers might work to fix it.
I concur on the quality of Norton software. They used to be reliable, oh, say, 15 years ago, but every encounter that I have had with them in the interim has ended with a crashed computer, and I'm not exactly clueless in that department
Their software is just way too invasive in my experience.
Regards,
Eric