JBPM4.0 执行流程的结点时，出现错误

当执行流程的结点时，出现错误，如下：
严重: Cannot delete or update a parent row: a foreign key constraint fails
2009-11-6 22:39:08 org.hibernate.event.def.AbstractFlushingEventListener performExecutions
严重: Could not synchronize database state with session
org.hibernate.exception.ConstraintViolationException: could not delete: [org.jbpm.pvm.internal.model.ExecutionImpl#1]

解决方法：
将jbpm.hibernate.cfg.xml文件中的org.hibernate.dialect.MySQLDialect改为org.hibernate.dialect.MySQLInnoDBDialect