On Windows 7 I have an ant target that copies a xalan library into the jdk endorsed directory so that the next xslt transformation task can occur. The first time that the ant target runs, the xslt transformation fails. The second time it runs the jar file is already in the correct place and the xslt tranformation succeeds. The first time that the ant target runs, it looks like the file copied successfully. It feels like a timing issue, but I don't know what I can do to get around it. Here is my copy task: <mkdir dir="${java.home}\lib\endorsed"/> <copy file="${basedir}\xalan.jar" tofile="${java.home}\lib\endorsed\xalan.jar"/> Has anyone seen anything like this before?