I know the feeling. I once went to open a wedding file folder I had downloaded from a CF and there was nothing there. Put the card back into the camera ... no images! None! After the panic attack subsided, I jumped through hoops looking for the shots somewhere, anywhere on my computer. Nothing. Even opened the trash. No love.Well done Edward - Marc - sometimes intended humour doesn't work, nice to see it resolved so nicely.
I was shooting a wedding in Holland a few weeks ago - all the ceremony shots were on a digital M. right at the end I was chimping and it came up with 'card read error' -scrolling back all I could see were the file names.
I had time to nip back to the hotel before the reception and had a cold shower whilst the images downloaded . . . they were all fine, but I don't want to go through that again.
You can't protect yourself against everything, and of course, if you have a camera fault it could be writing garbage to both cards. There isn't a perfect solution, but covering one's backside is a special requirement at weddings!
Later I restarted my computer and didn't realize I had left the CF in the reader ... during start-up my old virus scan was working and I noticed it scanning the camera files. I opened the CF card and then looked in the trash and there they were. Somehow, all the images had been deleted ... probably user error but darned if I remember doing anything of the sort.