The problem reported as bug 631597 was worked around by booting with "processor.nocst=1" parameter (solution was found in https://bugzilla.redhat.com/show_bug.cgi?id=727865 thread). Does it solve also 63274 and 630031 bugs? This is only a workaround. The real problem is probably somewhere in the ACPI BIOS. -- Regards, WZab