So I went out this morning and shot for a few hours. Get home, pull out the CF card and downloaded...nothing. Pull out the SD card and downloaded. My images show up but they're JPEG's! I don't shoot JPEG's. Check the menu on camera - yep, primary slot CF, secondary slot SD, secondary assigned as overflow, images shot as RAW. After checking these I shot an image, downloaded the CF card and there is my RAW image. Is my camera playing an April Fool's joke on me a couple of days late?
I have surmised that possibly the CF card didn't re-seat correctly after the last usage and so images went to the SD card, but as JPEG's? Weird. I welcome any rational explanations.