1st, rendering is not the same as exporting... so... what are you doing... rendering for timeline playback, or exporting to an output file?
2nd, More information needed for someone to help... please click below and provide the requested information
-Information FAQ http://forums.adobe.com/message/4200840
I'm exporting the project to an output file. I'm using CS6 with 6.0.2 update on a Mac OSX v10.6.8. I'm not using any third party software in the project. I'm using the same process I used when attempting to export using CS5.
The footage I'm using is H.264, Linear PCM. I do not get an error message, the exporting just stops at about 40% during both attempts.
That could indicate there's something in your sequence at that point that PP just doesn't like. I've seen 'corrupt' clips work fine on playback, but only stall during renders and exports. So give that section a good look.