I noticed my C drive was nearly full - some investigation revealed my hiberfil.sys file was 26 GB.
Doing some more reading showed this is linked to the hibernate feature, and the suggestion is to turn it off - however it is already turned off, so how do I get rid of the file?
I note that "Turn on fast startup" is turned on - could this be using the file?
I'm on Windows 8.1 Pro version 6.3 build 9600 (this is off Winver).
I'll attach some screenshots: