The errors are no big deal - more than likely the file system that the utmpx file is normally on has been dismounted for the reboot. You are getting the errors as one of the last parts before the system is down, correct?
(Something like this)
Print services already stopped.
The system is down.
INIT: failed write of utmpx entry:"s5"
INIT: failed write of utmpx entry:"of"
syncing file systems... done
As far as your desktop, save it, exit, log back in. No reboot is needed.