I have a feeling it occurs when I shut off the camera too quickly. Sometimes while processing the JPEG file in-camera.
I have a tendency (one which I must quit) when I see a moment to capture is to quickly pull the camera out, switch on, snap and switch off immediately.
My CF card is a 64GB Transcend rated at UDMA7 400X. It is brand new. The SD card is also Transcend brand, 16GB class 6, MicroSD which has been in many of my past gadgets (PSP, other past digital cameras, cell phones) and has proved to be extremely reliable.