With 1.507 I got following load errors while starting Jenkins (1.506 don't have this problem):

Mar 25, 2013 11:34:04 AM jenkins.InitReactorRunner$1 onTaskFailed
SEVERE: Failed Loading job intapp_vehicle
java.lang.NullPointerException
at hudson.matrix.MatrixProject.getItem(MatrixProject.java:669)
at hudson.matrix.MatrixProject.getItem(MatrixProject.java:662)
at hudson.matrix.MatrixProject.getItem(MatrixProject.java:98)
at hudson.model.AbstractProject.onLoad(AbstractProject.java:291)
at hudson.model.Project.onLoad(Project.java:83)
at hudson.matrix.MatrixConfiguration.onLoad(MatrixConfiguration.java:89)
at hudson.matrix.MatrixProject.loadConfigurations(MatrixProject.java:541)
at hudson.matrix.MatrixProject.loadConfigurations(MatrixProject.java:548)
at hudson.matrix.MatrixProject.rebuildConfigurations(MatrixProject.java:585)
at hudson.matrix.MatrixProject.onLoad(MatrixProject.java:476)
at hudson.model.Items.load(Items.java:221)
at jenkins.model.Jenkins$17.run(Jenkins.java:2552)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:146)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:887)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)