Unable to add the host to cloudstack

[Francis]

2013-03-07 16:11:19,243 ERROR [kvm.storage.LibvirtStorageAdaptor]
(Agent-Handler-1:null) org.libvirt.LibvirtException: operation failed:
Storage source conflict with pool: '8e109043-ef57-4d91-9239-296d8a47f2a3'

2013-03-07 16:11:19,245 WARN  [utils.nio.Task] (Agent-Handler-1:null) Caught
the following exception but pushing on

java.lang.NullPointerException

        at
com.cloud.hypervisor.kvm.storage.LibvirtStorageAdaptor.createStoragePool(Lib
virtStorageAdaptor.java:462)

        at
com.cloud.hypervisor.kvm.storage.KVMStoragePoolManager.createStoragePool(KVM
StoragePoolManager.java:57)

        at
com.cloud.hypervisor.kvm.resource.LibvirtComputingResource.initialize(Libvir
tComputingResource.java:3271)

        at com.cloud.agent.Agent.sendStartup(Agent.java:320)

        at com.cloud.agent.Agent$ServerHandler.doTask(Agent.java:850)

        at com.cloud.utils.nio.Task.run(Task.java:83)

        at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:11
10)

        at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:6
03)

        at java.lang.Thread.run(Thread.java:679)