Symantec Endpoint Protection will not install because it says Pending system changes that require a reboot have been detected

Delete the key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations

You may also need to check for the key at these locations:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSetXXX\Control\SessionManager\PendingFileRenameOperations
Where XXX is a number. Again, delete the PendingFileRenameOperations.

Do not reboot, just try the install again.