Comment 26 for bug 734777

I had the same problem.

Running RHEL5.6 host machine with latest patches as of today.

# lsb_release -r
Release: 5.6

# uname -a
Linux lark.cs.unc.edu 2.6.18-238.9.1.el5 #1 SMP Fri Mar 18 12:42:39 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

# rpm -qa|grep virt
virt-manager-0.6.1-13.el5
libvirt-0.8.2-15.el5_6.3
libvirt-0.8.2-15.el5_6.3
python-virtinst-0.400.3-11.el5
libvirt-python-0.8.2-15.el5_6.3

Installed a RHEL6.0 virtual machine, install went fine. The install rebooted at the end, the virtual machine window hung, the virt-manger window hung, let them sit for 5 minutes or so then killed them. Have 2 other old virtual machines that continued to run. Tried to start the new machine:

virsh # start lark-virtx
error: Failed to start domain lark-virtx
error: Timed out during operation: cannot acquire state change lock

Stopped librvirtd:

service libvirtd stop

Removed run directory:

rm -rf /var/run/libvirt

Note after the shutdown there was no /var/run/libvirt.pid file

Started libvirtd:

service libvirtd start

Was able to use virt-manager to start the new virtual machine.

Thanks Adrian, that worked!