CentOS virt - Mar 2008 - Xen Windows Clients - BSOD with Application Firewall Installs

I have set up both Windows XP and Windows 2000 Server clients on Xen under
Centos 5.1 and am unable to install an application
firewall.
I have tried the latest:
1) Agnitum Outpost Commercial Version
2) Comodo Firewall (ver 2 on Windows 2000)
3) Sunbelt Commercial Version

With all of these when the firewall starts up it results in a BSOD.
With Windows XP and Agnitum I can go back to a previous system restore point,
with Windows 2000 and other firewalls on XP the only
option is a backup of the Xen client as even a save mode command prompt startup
results in a BSOD.

I have tried on the Windows XP install using various HALS and switches for PAE
ACPI and multi/single cpu support and have not had
any success.

Windows 2000 BSOD results from "an attempt was made to write to read only
memory" NDIS.SYS

Windows XP BSOD message is related to:
Agnitum - sandbox.sys
Others: "an attempt was made to write to read only memory" NDIS.SYS

Has anyone any idea of how to set up Xen Windows clients to allow an application
firewall to be installed successfully?

Thanks


Jesse