I have a weird problem. When browsing my photo folders certain images (more than 50% of them) don't show up as thumbed previews. Imagine yourself browsing a folder with images where at most half of them show up as a thumbnail and the rest only as a filetype-icon.
These photo's are taken with my digital camera and *unedited*. In "certain other operating systems" (such as Windows and OS X) there's no problem, so it looks like it's got something to do with how KDE handles the magic-image-preview-mode-machine.
When I try to refresh the folder it stays the same. I.e. the same images are visible as a thumbnail, and the same images aren't at all. But when I open one of the mysterious-bad-images there's no problem (KDE will display them perfectly), the problem only appears when he's got to show the previews.
This problem also appears when browsing a folder in the GIMP.