Hello,
Could you please let us know if this is happening on only 1 machine or all machines??
If this is happening only on 1 machine, please Uninstall Network Threat Protection and Application and Device Control, Restart the machine and Reinstall the Network Threat Protection and Application and Device Control again and Restart the Machine again.
This could be done by:
1) Go to Control Panel, Add/Remove Programs
2) Highlight Symantec Endpoint Protection
3) Click on "Change"
4) Click on Modify
5) Uninstall Network Threat Protection and Application and Device Control.
6) Click on Finish
7) Restart the machine
8) Perform the Steps 1-8 again, however, this time to Install Network Threat Protection and Application and Device Control.
Hope that helps!!