I\'m a newcomer to Ubuntu, Hadoop and DFS but I\'ve managed to install a single-node hadoop instance on my local ubuntu machine following the directions posted on Michael-No
Have a look at the logs in the following path (based on the information supplied above):
$HADOOP_HOME$/logs/userlogs/job_201303081155_0032/task_201303081155_0032_m_000003
This should provide you with some information on that specific task.
The logs supplied by Hadoop are pretty good, it just takes some digging around to find the information :)