NIS and FIOS Issues

I recently installed Verizon FIOS (fiber optic) service at home.  I'm running Windows Vista Home Premium (Windows Firewall disabled) and Norton Internet Security.  Since the FIOS install, I have had repeated problems with my internet connection.  It's slow, and I am frequently bumped from "Local and Internet" to "Local Only".  When I disable the Norton "AutoProtect" and Firewall, this seems to resolve the issues.  Is there a compatibility issue between NIS and FIOS?

 

Thanks,

Peter