Look at your desktop. Look at the icons. Now look at the text beneath those icons. It's coloured, with a dropshadow beneath it, right? Right. Now, somehow I managed to turn this off and change it to the old "have a coloured block behind the text" mode. I know I turned this off because I remember doing it. However a good look through my Display Settings has revealed no option to go back to the old dropshadow method.

Anyone know how to turn it back on?

Control Panel > System > Advanced tab > Performance (Settings) > Check "Use drop shadow for icon labels on desktop".

Hoorah! Thanks.