" Are you running anything which is trying to set the hwclock in " dom0? It's best to leave well alone and let Xen do this.

At shutdown the xen0 does try to set the hwclock. Right after stopping ntpd, debian tries to save the system time to the hardware clock.

With yesterday's time fix, 7 of 16 hosts hang trying to shutdown. The one hung host on which I have a console is trying write the hardware clock. From previoius experience, I suspect if left alone an hour or so they will complete their shutdown and reboot.