I'm trying to render my movie i made on Kdenlive, and it usually just says that render is done when it is already probably under 10%! When i try to play that video, it is unplayable. What is problem, i use Ubuntu 12.04 64-bit.

I think this won't help, i still put it here.
Started render process: "/usr/bin/melt" "/tmp/kde-kissa/kdenlivesc2865.mlt -profile atsc_1080p_60 -consumer avformat:/home/kissa/Videot/jokuvideo.avi progress=1 acodec=libmp3lame ab=128k ar=44100 vcodec=libxvid minrate=0 vb=8000k aspect=@16/9 mbd=2 trellis=1 mv4=1 threads=4 real_time=-1"
Rendering of "/home/kissa/Videot/jokuvideo.avi" finished
Why it just says on about 4% suddenly that it's done, and then when i try to play it isn't playable. What is going wrong?

What version of Kdenlive and what version of MLT ?

Because there are some known issues like this with earlier versions eg 0.9.0 and 0.9.1 (from memory). 0.9.2 is recommended.