Problems on MP4 clip

Now i'm started to use kdenlive.
I have to use a mp4 files of my Sanyo fullHD cam.
I've noted there are some problems on reproducing some clips.
The problem are on the original clip (in kdenlive monitor) and on the exprted files.
When on the clip thera are a most part black on the screen, appeare some withe dots or withe rows, non present on the original clip.
The stange issue is that problem is present only on the new notebook (intel i3 cpu) and not on the old workstation (AMD Semperon).
So I think that the problem is about some "optimization " for the intel cpu, like on cinelerra.
What's about ?

UPDATE

I Think that i've solved my problem (kubuntu 10.04 64 bit)
The only diffent pakage was melt.
On the new notebook (fresh installed and uptaded) it's present only 0.5.4.1 version from ubuntu repo.
On the old workstation it's present version 0.5.6.0 (newer) from a old repo deb http://ppa.launchpad.net/sunab/ppa/ubuntu...

I don't know why it's no present on the new notebbok.
I've instlled the new/old repo (and the updated melt seems to work.
I've only a error from synaptic abaut duplicated repo, i think that the problem is on the automated repo updating from akirad (cinelerra)

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