So ive just done a fresh install of my computer, due to ubuntu 12.10 being too unstable. Ive installed Ubuntu 12.04 64 bit, with the unity interface. so far its been great. (also got dual monitors setup)
So i copied over the daily build of ubuntu i had been previously using, worked perfect, except that rendering finishes in around 3 seconds, the outputed video file is tiny and doesnt play, so its obvioiusly not rendered anything and just wrote an empty file.
Kdenlive installed from the PPA from here does the same thing. so its not the daily build.
I have also tried different render profiles, they all do the same thing.
Any ideas why this is not working?
This is a fresh install of Ubuntu 12.04 and the only difference really is ATI graphics card with ATI's catylist drivers installed (fglrx-legacy with downgraded x server 1.12 as 1.13 doesnt support amds legacy driver, but dont see how this should affect rendering)
I've also upgraded my ram with 2 2gb ram modules (had 1gb and 2gb before)

After some searching, i found an old post that mentioned try running it with sudo.
sure enough running the daily build i have using sudo, and its now rendering.
this is strange.