You get multiple Winlogon.exe – No disk in drive errors on shutdown of Windows 8. Additionally, the PC hangs in a powered state, even though the monitor has switched off. Initially I thought this was due to driver issues with the PC’s card reader, however stumbled on this excellent blog http://www.ptmaroct.com/2012/06/fix-windows-8-rc-shutdown-errors.html.
Disabled fast start up (search Control Panel for “Change what the power buttons do”) – the errors magically disappeared and the PC now shuts down. Thanks !