Hi! I have a machine that won''t boot the xen kernel if I don''t use the acpi=off option when booting. If I don''t use I have kernel panic. This machine have Ubuntu 12.04 with kernel 3.2 installed and Xen 4.1 installed using apt-get. This all works fine, since I''ve added the acpi=off when booting in the kernel with xen. In the last few days I did an upgrade to the machine, from 12.04 to 12.10, and the kenel was also updated to 3.5. The problem is that when trying to boot with acpi=off in the xen kernel, the system hangs with a lot of messages about the hard drives, and after a while it keeps informing I/O error in the disks. When booting in the same kernel but without xen, the boot works normally. Since I had to have the a VM online, I''ve reinstalled the 12.04. I''ve another machine that presented the same error, but I was able to remove the acpi=off from the boot line and it worked (that machine was brand new and not using acpi=off wasn''t an issue). But the curious thing, is that using acpi=off with xen on that machine causes the same errors I''m experiencing with the older machine. Anyone have any idea why the apic=off may be doing this? Thanks a lot, Vinicius