SEP is blocking websites from working on W2k3 servers.

We are seeing issues with SEP 12.6 on Win2k3 webservers where the websites become unavailable. If we disable Network Threat Protection, the sites become available once again. We can re-enable it and the websites will contrinue to work for some period of time until it happens again. How do we acertain what is causing this and how do we prevent it from causing the website unavailabilty?

Thanks,

DeShark