Full system scan over in a few seconds

Hi

I am on windows 10 using the latest norton 360 (just ran the norton removal reinstall tool) Just updated the virus database

When I click full system scan it only takes a couple of seconds and then says no threats found

If I click quick or custom scan it runs fine.  Also the scan sometimes hangs for a few hours and then I cannot quit it until I reboot

On a side note, every time I reinstall norton it says trusteer endpoint protection is incompatable but I always ignored it except today I opted to uninstall it but the problem is persisting with short/never ending scans

Any help appreciated