Hi!
In my Case (HP DL145 Single SingleCore Opteron) it was helpful to turn of acpi and apic:
Try changing your grub.conf to:
==============grub.conf============== title Fedora Core (2.6.16-1.2080_FC5xen0) root (hd0,0) kernel /xen.gz- 2.6.16-1.2080_FC5 noacpi noapic acpi=off module /vmlinuz-2.6.16-1.2080_FC5xen0 ro root=/dev/VolGroup00/LogVol01 noacpi noapic acpi=off module /initrd-2.6.16-1.2080_FC5xen0.img ==============End of grub.conf==============
HTH, chris
Mit freundlichen Grüßen, /// Kind Regards, Christian Reiter