Hello,
There are typically several reasons why teefer fails to install... the one that is most common is the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DevicePath is not correct (it must be a REG_EXPAND_SZ key)
OR
The Network Threat Protection driver normally loads after a reboot of the computer as a device driver. If the path to the location of the .inf file is not in the device path, the driver installation will fail.
Could please try the Steps below to resolve the issue.
1) Go to Add / Remove Programs and Highlight "Symantec Endpoint Protection" and Click on "Change"
Uninstall Network Threat Protection
Restart the machine
Again, Go to Add / Remove Programs and Highlight "Symantec Endpoint Protection" and Click on "Change"
Reinstall Network Threat Protection and Restart the machine again.
2) Check the registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DevicePath" the value should include %systemroot%\inf, if the entry is missing or blank, the data value should be added. A reboot is required for the change to take effect.
http://www.symantec.com/docs/TECH94974
3) TCP/IP and Windows networking must be installed and configured in order for the Teefer driver to be inserted into the IP stack.
Install the Internet Protocol (TCP/IP) by clicking the "Install" button on the "General" tab of LAN properties. This will need the Windows CD ROM to complete the installation.
http://www.symantec.com/docs/TECH131614
Hope that helps!!