common error in map tasks

[kaveh minooie]

HI

regardless of what job I run, there are always a few map tasks that fail 
with the following, very unhelpful, message: ( that is the entire error 
message)

java.lang.Throwable: Child Error
        at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:271)
Caused by: java.io.IOException: Task process exit with nonzero status of 126.
        at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:258)


I would appreciate it if someone could show me how I could figure out 
why this error keeps happening.

thanks,