Rendering problem relates to MLT version I think, kdenlive 0.9 from sunabs PPA and from build script work, I too had rendering issues with previous build. Make sure MLT is upto date.

Blocking at movement in frame: Can you post your image here please, I'm not a member of Ubuntu forums. Sounds like a threading problem when decoding your MTS. If threads is set to 1 then it should work, by default kdenlive does this, have you changed number of threads? Anyways image would be good.

I'm have the same problem on Ubuntu 12.04 x64 with latest sunab/kdenlive-release packages.
Any render aborts with the next errors:

?????? /home/zheka/projects/kdenlive/2011-12-28 ???????.avi ???????? ????????
[mp3 @ 0x259d160] max_analyze_duration reached
[mp3 @ 0x25b96a0] max_analyze_duration reached
[mp3 @ 0x7fdda4006280] max_analyze_duration reached
[mp3 @ 0x7fdda4037520] max_analyze_duration reached

I tried different formats and filenames without spaces - it don't helps!

Garp! Do you really render any mode in two pass?
I have add kdenlive-svn repo and update and upgrade system. It reinstall current kernel (???), delete python-mlt and change mlt4 to mlt5.
MPEG2 2 pass work, xvid4 1 pass work, but xvid4 two pass render don't work!!!

But I don't purge anything just upgrade the system!

I'm running Ubuntu 12.04 x64

Thanks, I'll be trying to full uninstall and reinstall only from svn later.
Now I have the same problem as before: http://www.kdenlive.org/forum/2-pass-xvid4-encoding-crash
There are current errors:
[mp3 @ 0x259d160] max_analyze_duration reached
[mp3 @ 0x25b96a0] max_analyze_duration reached
[mp3 @ 0x7fdda4006280] max_analyze_duration reached
[mp3 @ 0x7fdda4037520] max_analyze_duration reached
*** glibc detected *** /usr/bin/melt: double free or corruption (!prev): 0x0000000004beb7a0 ***

I just cleared the system from any bites of kdenlive related packages. Clear apt cache and reinstall all from ppa:kdenlive-svn.
Problem still the same (see http://www.kdenlive.org/forum/2-pass-xvid4-encoding-crash).
I tried MPEG2 and MPEG4 two pass encoding - all work, but XviD4 two pass encoding don't work!!!
But I find a solution!!!
Not elegant but just work!!!
Run in terminal:

MALLOC_CHECK_=1 kdenlive

This overrides some memory checks (glibc detected errors) for running process.
Two pass XviD4 encoding works without any problem!!!
Resulting video file also without any problem!

I saw the terminal output for this work:
There are messages before encoding starts:

[mp3 @ 0x259d160] max_analyze_duration reached
[mp3 @ 0x25b96a0] max_analyze_duration reached

But there are not any errrors or messages between first and second pass!!!
There are not any output after works ends!
All works fine!

have almost the same problem few days ago: can't render in any format
try to reinstall all kdenlive related packages:
kdenlive, frei0r-plugins, mlt, libmlt, melt, python-mlt
delete ppa:sunab/kdenlive-release if it is
add ppa:sunab/kdenlive-svn
reinstall all from this ppa
in my case all work expects xvid4 two pass encoding
Running MALLOC_CHECK_=1 kdenlive makes xvid4 two pass encoding working :-)
You can try MALLOC_CHECK_ with 0

[deleted - I had the wrong libs recovered ]

You do not have to create a script to render. Kdenlive should start a render job and render to completion. But if the script you generated crashes this is suggesting you have some issue. Which might explain why the render job never completes.

Version 0.8 is not supported. You should upgrade to 0.9.2. It fixes a number of rendering bugs.

@nomad062, have you tried the build script, http://www.mltframework.org/bin/view/MLT/BuildScripts until Mint adds 0.9.2 to it's repos?

I solved this problem completely start Kdenlive from the terminal with "sudo kdenlive"

terminal start does not work for me..

I have tried everything still crashes on me when rendering hope a fix comes soon...