I observed this behaviour on a xen host running precise 12.04.2.
Happened two times up to now with the ubuntu kernel 3.2.0-39-generic and xen 4.1.2.
The machine was hosting a Ubuntu Linux 12.04.2 HVM and a Windows XP HVM.
There was nothing suspicious in the log of the (Linux) guest.
Attached is the relevant part from the dom0 kernel log.
I observed this behaviour on a xen host running precise 12.04.2.
Happened two times up to now with the ubuntu kernel 3.2.0-39-generic and xen 4.1.2.
The machine was hosting a Ubuntu Linux 12.04.2 HVM and a Windows XP HVM.
There was nothing suspicious in the log of the (Linux) guest.
Attached is the relevant part from the dom0 kernel log.