i converted some a pdf to a series of images (png) and tried to add them to kdenlive but they show distorted and sometimes crash kdenlive.
I converted them to jpegs but they do the same thing.
I then tried other pngs and jpegs and they work perfectly.
I'm using kdenlive svn and know it is development , but since it only happens with certain images it might be in 7.8 too.
My system is archlinux and I uploaded one of the pngs so that anyone who wants test it can try http://www.mediafire.com/?dwt8ia5jkpthfh9

this is my ffmpeg information incase it matters.
FFmpeg version git-2611e52
libavutil 50. 36. 0 / 50. 36. 0
libavcore 0. 16. 1 / 0. 16. 1
libavcodec 52.108. 0 / 52.108. 0
libavformat 52. 94. 0 / 52. 94. 0
libavdevice 52. 2. 3 / 52. 2. 3
libavfilter 1. 74. 0 / 1. 74. 0
libswscale 0. 12. 0 / 0. 12. 0
libpostproc 51. 2. 0 / 51. 2. 0