Vista - Windows hosts file and Norton (NIS 2008)

Today I noticed that when I run NIS 2008 security inspector (when going on stage to check IP adresses) it just remove all entryes in hosts file in Windows/System 32/Drivers/etc
However,when I run Spybot S&D it cretae new host file with over 8000 entries but when I run Security inspector it's just delete all entries
Is this normal?
Checking my image file created with Acronis Home (which contains ONLY Windows Vista SP1 and no other software) I noticed that also hosts file is empty too.
In both (image file and curent Windows Vista SP1) in hosts file (opened with notepad) entry is this:

# Copyright (c) 1993-2006 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host

127.0.0.1 localhost
::1 localhost

Runed full system scan with NIS,Spybot and Kaspersky online scaner and nothig found

I'm very confused,what's going on (or wrong)

Vista SP1 32-bit NIS 2008 15.5