I have two boxes using the same install of maven and a project which consists of a parent and 4 children: two jars, one war, one ear. On one box everything works fine, on the other, running 'mvn clean' causes the triggered 'cobertura:clean' to fail in the ear-project complaining that it cannot find the maven-ear-plugin or a valid version of it. What could be causing this failure on one box and not the other?