Network problem on ths host server with Virtual Server 2005 SP1 R2

HEllo

I have a problem on a MS VS 2005 SP1 R2 on windows 2003 R2 X86 server.
Each time i start a VM on a virtual network bind on one of my 4 NICS, i
loose network connectivity on the host. VM with internal network is OK,
when the VM starts host connectivity is not lost
I have the same server with same hardware & software config wich works
without any problem.
I tried to uninstall & reinstall MS VS after removing the "C:\Documents
and Settings\All Users\Application Data\Microsoft\Virtual Server"
without any success.

Here is my Options.xml file :

<?xml version="1.0" encoding="UTF-16"?>
<!-- Microsoft Virtual Machine Options and Settings -->
<preferences>
<version type="string">2.0</version>
<properties>
<modifier>
<build type="string">1.1.603.0 EE R2 SP1</build>
<name type="string">Microsoft Virtual Server</name>
</modifier>
</properties>
<settings>
<virtual_server>
<enable_hw_assist type="boolean">true</enable_hw_assist>
</virtual_server>
<remote_control>
<vmrc>
<authentication>
<type type="integer">2</type>
</authentication>
<enabled type="boolean">true</enabled>
</vmrc>
</remote_control>
</settings>
<virtual_gateway id="0">
<id type="integer">0</id>
<type type="integer">0</type>
</virtual_gateway>
<virtual_gateway>
<next>
<virtual_gateway_id type="integer">20</virtual_gateway_id>
</next>
</virtual_gateway>
<virtual_gateway id="1">
<adapter
type="string">\DosDevices\VPCNetS2_{4D918CD2-C009-4E55-B330-F9A412E43558}</adapter>
<id type="integer">16</id>
<name type="string">Intel(R) PRO/1000 PT Dual Port Server Adapter</name>
<type type="integer">2</type>
</virtual_gateway>
<virtual_gateway id="2">
<adapter
type="string">\DosDevices\VPCNetS2_{2AE30925-4414-438B-9F4F-386E7721417C}</adapter>
<id type="integer">17</id>
<name type="string">Broadcom BCM5708C NetXtreme II GigE (NDIS VBD
Client) #2</name>
<type type="integer">2</type>
</virtual_gateway>
<virtual_gateway id="3">
<adapter
type="string">\DosDevices\VPCNetS2_{3EB43F41-EF66-4256-94CE-2F3E82B26638}</adapter>
<id type="integer">18</id>
<name type="string">Intel(R) PRO/1000 PT Dual Port Server Adapter
#2</name>
<type type="integer">2</type>
</virtual_gateway>
<virtual_gateway id="4">
<adapter
type="string">\DosDevices\VPCNetS2_{E6C88B5E-3174-4757-8078-A97E6D412262}</adapter>
<id type="integer">19</id>
<name type="string">Broadcom BCM5708C NetXtreme II GigE (NDIS VBD
Client)</name>
<type type="integer">2</type>
</virtual_gateway>
</preferences>

thks for helping me
Fadoul