I have spent hours on the phone with Norton and then with Symantec. They have finally pointed me here.
My university had a site licence of Symantec Endpoint protection. We've moved to another provider last year.
I recently tried to uninstall Endpoint Protection on my Mac (and I have run the special cleanwipe file from the Symantec site). There remain Norton/Symantec files all over my computer which seem to be locked, and I am unable to install new anti-virus software.
Help?????
I've signified version 10.x above, as I'm unsure what version we were running. It's probably more recent than 10.