Hi,
Please ff the procedure below. I've encountered this before and this was the resolution given by symantec technical support.
Ensure that the following features are disabled:
Control Panel > User accounts > User account control
Control Panel > Windows Defender
Control Panel > Windows Firewall
Control Panel > Folder options > View > Advanced > Simple File Sharing
Perform the following steps:
1. Uninstall LiveUpdate if it exists in Add/Remove Programs.
2. Reboot the computer.
3. Installed LiveUpdate3.5 in compatability mode.
4. Created SEP full package (not single.exe) from SEP Manager.
5. Initiated SEP installation by running Symantec Antivirus.msi from the setup package.
just inform me how it goes.
if able to resolve your problem please mark it as solution