on render by mp4 the render process hangs but the software don't.

[Mohammed Al Mubarak]

When I choose render the render window apear and the render process goes until at some point it seems hangs. the progress does not proceed, the file size does not increase but the apps still take user responces. tried any of the codecs gave same result.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: pitivi 0.15.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
ApportVersion: 1.23-0ubuntu4
Architecture: i386
Date: Tue Mar 27 23:26:16 2012
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=ar_BH:ar
 PATH=(custom, no user)
 LANG=ar_BH.UTF-8
 SHELL=/bin/bash
SourcePackage: pitivi
UpgradeStatus: Upgraded to oneiric on 2011-10-13 (166 days ago)