Vista - Increased network utilization on host

Hello,

I am running XP virtual machines on a Vista host using VPC. This has been
working very well until yesterday i notice if i start a virtual pc image,
the host network utilization shows 5% and my normal network activities on
the host computer either does not succeed or take a long time. Close all the
VPC images, things are fine.
I dont have anything conclusive to link this to automatic updates but I
started noticing it after automatic updates and restart on 3/11/2009.

Just checking to see if there are any explanations or similar experiences
out there.

Priyesh