Some days ago I was involved on a Windows 8.1 machine that take up to 60 minutes to boot.
On Application Event log I found this error:
Nome registro: Application
ID evento: 6006
Parole chiave: Classico
La gestione dell’evento di notifica (CreateSession) da parte del sottoscrittore delle notifiche di WinLogon ha richiesto 3599 secondi.
As first step I tried to move this machine on a OU without GPOs but nothing was changed.
Then I tried to check WMI status because WMI is checked during GPO analysis.
There is a good blog from “Performance Team”: http://blogs.technet.com/b/askperf/archive/2009/04/13/wmi-rebuilding-the-wmi-repository.aspx
This is what I did for solve the problem:
net stop winmgmt /y winmgmt /resetrepository
Then reboot the system.