Hi,
To disable fast boot in Windows 8, a user must first enable Hibernation, as you know, by opening an elevated command prompt and typing into it:
powercfg -h on
Once this is done, the 'Turn on Fast Startup (recommended)' option will appear in the Control Panel Power applet, under 'Choose what the power buttons do' option. (you first have to click 'Show options that are currently unavailable'). It was then a matter of un-ticking this option and restarting Windows.
Following your advice I was able to re-activate fast start mode and it is back to how it was, so thanks for that. I'm a little happier.
Sadly the whistling continues, endlessly. It's a varying high-pitched tone at about the pitch of someone whistling, that to my ears sounds like a failing capacitor. It is a real shame because the machine is almost silent, even with the system fan, until the whistling starts (and it always does once the desktop loads).