HBase won't start due to NodeExistsException in Zookeeper-based region assignment

2010-06-15 06:30:00,287 WARN org.apache.hadoop.hbase.zookeeper.ZooKeeperWrapper: 
<org.apache.hadoop.hbase.master.HMaster>Failed to create ZNode /hbase/UNASSIGNED/1766164500 in ZooKeeper^D
org.apache.zookeeper.KeeperException$NodeExistsException: KeeperErrorCode = NodeExists for /hbase/UNASSIGNED/1766164500^D
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:110)^D
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:42)^D
        at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:637)^D
        at org.apache.hadoop.hbase.zookeeper.ZooKeeperWrapper.createZNodeIfNotExists(ZooKeeperWrapper.java:974)^D
        at org.apache.hadoop.hbase.zookeeper.ZooKeeperWrapper.createUnassignedRegion(ZooKeeperWrapper.java:1053)^D
        at org.apache.hadoop.hbase.master.RegionManager.doRegionAssignment(RegionManager.java:355)^D
        at org.apache.hadoop.hbase.master.RegionManager.assignRegions(RegionManager.java:312)^D
        at org.apache.hadoop.hbase.master.RegionManager.assignRegionsToMultipleServers(RegionManager.java:292)^D
        at org.apache.hadoop.hbase.master.RegionManager.assignRegions(RegionManager.java:221)^D
        at org.apache.hadoop.hbase.master.ServerManager.processMsgs(ServerManager.java:500)^D
        at org.apache.hadoop.hbase.master.ServerManager.processRegionServerAllsWell(ServerManager.java:425)^D
        at org.apache.hadoop.hbase.master.ServerManager.regionServerReport(ServerManager.java:335)^D
        at org.apache.hadoop.hbase.master.HMaster.regionServerReport(HMaster.java:700)^D
        at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)^D
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)^D
        at java.lang.reflect.Method.invoke(Method.java:597)^D
        at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:576)^D
        at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:919)