Comment 6 for bug 931540

The same problem here. Can be fixed by:

sudo service libvirt-bin stop && sudo service libvirt-bin start && sudo service nova-compute restart

Waiting for bug fix.

Some info:

Distributor ID: Ubuntu
Description: Ubuntu 11.10
Release: 11.10
Codename: oneiric

Package: libvirt-bin
Priority: optional
Section: devel
Installed-Size: 3680
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Debian Libvirt Maintainers <email address hidden>
Architecture: amd64
Source: libvirt
Version: 0.9.2-4ubuntu15

Package: nova-compute
Priority: extra
Section: net
Installed-Size: 96
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Openstack Maintainers <email address hidden>
Architecture: all
Source: nova
Version: 2011.3-0ubuntu6

Can give more info. Logs, configs, ...