I think in future release of Kdenlive to have such tool somewhere in the menu, to generate small text report about kdenlive and most important parts, so will be much easier to see before any answer what's wrong, so everyone could copy and paste it into eg. forum or buglist. Now kdenlive can use ffmpeg or libav, in many distribution available ffmpeg is now quite old (in compare to libav) or the same version of kdenlive use different mlt, so maybe the same version of kdenlive may behave in different way. Not everyone knows which version of which sub-packages kdenlive use, and in this way will be generated automatically. I had eg. problem with Av out of sync with kdenlive from 0.7.8 to 0.8.2 - the problem solved mlt 0.8.6, not kdenlive update. So we could have someone with the newset kdenlive (0.9.4) but oldest mlt (eg. 0.8.2) with AV out sync issue - this may be on bug list for ths case, it might be a big discussion, but simply update of mlt cold solve the problem.

Bellow eg. file

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kdenlive 0.9.4
mlt 0.8.8
ffmpeg 0.10.6
libav -----
frei0r-plugins 1.3
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