I had the same problem with a Kingmax 1 GB card in my FZ20. Some pictures were missing when viewing in-camera, and the same ones were missing when viewing on the computer with card reader. Then the problem progressed to not being able to write to it or format it in the camera. The strange part is that l can still format, copy pictures to it and view them with the computer & card reader. It just doesn't work in the camera. Several other SD cards work well in the camera, so it is not a camera problem. So now I'm using the Kingmax card as a flash drive for the computer, so it wasn't a total waste. I replaced that card with a Sandisk Ultra 2 1GB and it is great. Bottom line: I won't buy another Kingmax card.
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Zoomster