Hi all,

I have an Ubuntu 10.04 physical host running KVM. This host runs several
Ubuntu 10.04 VMs, one of which is running Zimbra
(7.0.1_GA_3105.UBUNTU10_64 UBUNTU10_64 NETWORK).

5 times since September last year I've had just this VM completely lock
up at seemingly irregular intervals, and I can find no pattern as to why
it's happening, but would like to either be able to confirm or discount
Zimbra as a cause.

When the lock-up occurs, I can't ping the VM, view its console (using
the KVM VNC console; it just sits there not even loading a blank
screen), or shutdown the VM. When I try to shut it down, nothing appears
to happen, and if I then try to kill the VM, the dead (zombie) process
stuck around, and KVM thought it was still running, so wouldn't let me
start it back up without rebooting the physical host. In 4 out of 5
cases, all other VMs and the host OS were unaffected. In the 5th, all
VMs locked up.

Has anybody seen anything like this before?