After booting and logging on, I notice two instances of the userinit.exe process. The first terminates normally. The second hangs on, without any child processes, for an indeterminate period of time. Sometimes it exits after a few minutes, sometimes never. When the second instance is running, a shutdown or logoff takes several minutes (>5 mins, when all other applications are already shutdown). The is only one mention of userinit.exe is in the registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit.