For Symantec Endpoint Protection 12.1...run Symantec Help (SymHelp)
Symantec Help (SymHelp) is a utility designed to quickly and efficiently diagnose common issues encountered on multiple Symantec products. SymHelp can identify most of the problems that you might run into when installing the client, and provide instructions on how to solve them. If SymHelp cannot identify the problem, it can create a detailed report that you can submit to Technical Support to identify the problem.
In addition to checking system requirements the following Pre-Installation Tests will be performed
Is the Windows Installer service disabled?
About the Find Unmanaged Computers function in Symantec Endpoint Protection Manager
Does the computer need to be restarted?
Does the current user have local administrator rights?
Does the Administrator account have a password?
Is the local security setting “Sharing and security model for local accounts” set to Guest Only?
Is User Account Control enabled on the client?
Are the C$, ADMIN$ and IPC$ shares available?