We need six consecutive commits backported to F16, as this set of double-close bugs can cause rather insidious failures of libvirt.

b19c236d69278c967d2d8b4aae97ac76213f1c10 qemu: avoid closing fd more than once
746ff701e8727439cac8ca72531d82e5cb7fa129 command: check for fork error before closing fd
f3cfc7c8848006b613e09bb1acd081716854527e fdstream: avoid double close bug
da831afcf2f6c0d3ed1ea3128a6208f548a05d8f command: avoid double close bugs
655cffa0f25be40c68624036af80bde102177612 avoid fd leak
0a045f01cfa48fabd41c801e3f44034a4e6da485 avoid closing uninitialized fd

libvirt-0.9.6.1-1.fc16 has been submitted as an update for Fedora 16.
https://admin.fedoraproject.org/updates/libvirt-0.9.6.1-1.fc16

Package libvirt-0.9.6.1-1.fc16:
* should fix your issue,
* was pushed to the Fedora 16 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing libvirt-0.9.6.1-1.fc16'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2012-9913/libvirt-0.9.6.1-1.fc16
then log in and leave karma (feedback).

libvirt-0.9.6.1-1.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.