Netbeans 7 deploying to Glasfish 3.1 issue

[Andrew Dambrosio]

I've just installed Netbeans 7.0 and Glasfish 3.1
I opened my project and when I deploy, I get the following error:

 Error occurred during deployment: Exception while loading the app : java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: org.apache.catalina.LifecycleException: java.lang.NoClassDefFoundError: edu/emory/mathcs/backport/java/util/concurrent/ThreadFactory. Please see server.log for more details.

The module has not been deployed.
	at org.netbeans.modules.j2ee.deployment.devmodules.api.Deployment.deploy(Deployment.java:187)
	at org.netbeans.modules.j2ee.ant.Deploy.execute(Deploy.java:106)
	at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
	at sun.reflect.GeneratedMethodAccessor375.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
	at org.apache.tools.ant.Task.perform(Task.java:348)
	at org.apache.tools.ant.Target.execute(Target.java:390)
	at org.apache.tools.ant.Target.performTasks(Target.java:411)
	at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
	at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
	at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
	at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
	at org.apache.tools.ant.module.bridge.impl.BridgeImpl.run(BridgeImpl.java:284)
	at org.apache.tools.ant.module.run.TargetExecutor.run(TargetExecutor.java:539)
	at org.netbeans.core.execution.RunClassThread.run(RunClassThread.java:154)
BUILD FAILED (total time: 25 seconds)

Does anyone know what the problem would be?