I built guest vm's one for Windows 7 and one for Windows XP using the virtual machine manager on a just updated to centos 5.7, and they are both crashing the host machine. They run only for a few minutes, but suddenly freeze, crashing the host. There is no networking. No X. No way to drop out of X. The only way out is a hard reboot. I don't see anything in the logs -- messages or libvirt logs -- immediately before the crash. I haven't found anything like this on the web or on this list. The workstation has two xeon E5410s. I noticed that both the kvm-amd and kvm-intel modules are loaded, but don't know if that would cause a problem. I had an ati firepro graphics card in the machine, but suspected that might be the source of some conflict, and I put in an Nvidia card. The vm's were built with all the defaults. The configuration is just about identical to vms I have running on a smaller machine with a dual core Athalon. Thanks for any suggestions.