Vista - Strange communication issues with Host and guests.. help?

Suddenly, as of late.. some weird things have been going on on our virtual
server host machine with its guests..

I have two virtual server hosts... the first (Vserver01) is 2003 x64 with
about 9 guests.. one of these is a DNS/DHCP/DC 2003 guest..

The other host server has the other DC/DCHP/DNS virtual guest server..

Right now i cant ping any of the guests hosted on Vserver01.. but dns
appears to be functioning... (via the 2nd virtual DNS/DC machine)..

I also cant ping any of these guests by direct ip.. but.. if i goto the
virtual server console and browse to the machine.. i can log onto these
machines and they can ping each other, but not outward...

The only error i see in the virtual server event log is this:

Virtual Server has encountered a non-fatal exception. Details have been
logged to "C:\Documents and Settings\All Users\Application
Data\Microsoft\Virtual Server\Crash Logs\VSCrashLog16090231358.txt".

Details at the end of this file have:

Structured exception occurred on an undetermined or a global thread.

Prior to this i do see some errors about one of our virtual servers,
vsintranet01 starting back up, its a 2008 server:

The setting "integration/microsoft/version/guest_os/short_name" for the
virtual machine configuration "VSIntranet01" was changed from NULL to
"Windows Serverâ„¢ Codename Longhorn".

And also things like this:
The setting "integration/microsoft/version/guest_os/revision_number" for the
virtual machine configuration "VSIntranet01" was changed from NULL to
"Service Pack 1".

**This is virtual server 2005 R2 sp1 for x64**

I'm guessing its not a DNS issue since i cant even ping by direct ip address..

Its like the guests have lost communication with the nic card on the host
server... but i'm not sure what the 2008 server informational messages are
about either..

Any thoughts here?

Thanks