I am using Ubuntu server 11.10,with xen hypervisor 4.1. Beside this I have installed Libvirt-0.9.2. All things working perfectly. But some time while using virt-install or virt-clone during the installation of guest OS or during clone the screen truns to black with white letters and then it hangs. This occurs not during the boot or between using any program. Just while I am using terminal and use virt-install or virt-clone command line tools. Or some times when I am going to start more than 1 guest operating systems. I need to know why this appears and how can I solve this.