deleted entity passed to persist

Has anyone seen an error like this?  Sonar only fails for this project FooBar, but works for many others.

Maven 1.9.2
winxp

[07:57:32]: [INFO] FooBar [class org.sonar.plugins.core.SaveProjectLinksFromPom] executing
[07:57:32]: [INFO] ------------------------------------------------------------------------
[07:57:32]: [ERROR] BUILD ERROR
[07:57:32]: [INFO] ------------------------------------------------------------------------
[07:57:32]: [INFO] Can not start sonar-core-maven-plugin
[07:57:32]:
[07:57:32]: Embedded error: deleted entity passed to persist: [org.sonar.commons.resources.ProjectLink#<null>]
[07:57:32]: [INFO] ------------------------------------------------------------------------
[07:57:32]: [DEBUG] Trace
[07:57:32]: org.apache.maven.lifecycle.LifecycleExecutionException: Can not start sonar-core-maven-plugin
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:583)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:512)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:482)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:330)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:227)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
[07:57:32]: at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
[07:57:32]: at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
[07:57:32]: at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
[07:57:32]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[07:57:32]: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[07:57:32]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[07:57:32]: at java.lang.reflect.Method.invoke(Method.java:585)
[07:57:32]: at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
[07:57:32]: at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
[07:57:32]: at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
[07:57:32]: at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
[07:57:32]: Caused by: org.apache.maven.plugin.MojoExecutionException: Can not start sonar-core-maven-plugin
[07:57:32]: at org.sonar.mojo.bootstrap.BootstrapMojo.execute(BootstrapMojo.java:90)
[07:57:32]: at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:451)
[07:57:32]: at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:558)
[07:57:32]: ... 16 more
[07:57:32]: Caused by: javax.persistence.EntityNotFoundException: deleted entity passed to persist: [org.sonar.commons.resources.ProjectLink#<null>]
[07:57:32]: at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:614)
[07:57:32]: at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:300)
[07:57:32]: at org.sonar.commons.database.DatabaseSession.flush(DatabaseSession.java:148)
[07:57:32]: at org.sonar.commons.database.DatabaseSession.remove(DatabaseSession.java:131)
[07:57:32]: at org.sonar.mojo.ProjectContextImpl.removeLink(ProjectContextImpl.java:300)
[07:57:32]: at org.sonar.plugins.core.SaveProjectLinksFromPom.updateLink(SaveProjectLinksFromPom.java:79)
[07:57:32]: at org.sonar.plugins.core.SaveProjectLinksFromPom.collect(SaveProjectLinksFromPom.java:61)
[07:57:32]: at org.sonar.plugins.core.SaveProjectLinksFromPom.collect(SaveProjectLinksFromPom.java:50)
[07:57:32]: at org.sonar.mojo.InternalMojo.executeCollectors(InternalMojo.java:295)
[07:57:32]: at org.sonar.mojo.InternalMojo.processModules(InternalMojo.java:177)
[07:57:32]: at org.sonar.mojo.InternalMojo.execute(InternalMojo.java:156)
[07:57:32]: at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:451)
[07:57:32]: at org.sonar.mojo.bootstrap.MojoExecutor.executeMojo(MojoExecutor.java:42)
[07:57:32]: at org.sonar.mojo.bootstrap.BootstrapMojo.execute(BootstrapMojo.java:84)
[07:57:32]: ... 18 more