The process continues to run, but throws this exception:

Mar 19, 2014 1:34:54 PM hudson.model.ComputerSet <clinit>
WARNING: Failed to instantiate NodeMonitors
java.io.IOException: Unable to read /Users/jenkins/.jenkins/nodeMonitors.xml
at hudson.XmlFile.read(XmlFile.java:144)
at hudson.model.ComputerSet.<clinit>(ComputerSet.java:426)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:105)
at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:169)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:899)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:744)
Caused by: com.thoughtworks.xstream.converters.ConversionException: hudson.node_monitors.DiskSpaceMonitor cannot be cast to hudson.util.DescribableList : hudson.node_monitors.DiskSpaceMonitor cannot be cast to hudson.util.DescribableList
---- Debugging information ----
message : hudson.node_monitors.DiskSpaceMonitor cannot be cast to hudson.util.DescribableList
cause-exception : java.lang.ClassCastException
cause-message : hudson.node_monitors.DiskSpaceMonitor cannot be cast to hudson.util.DescribableList
class : hudson.util.DescribableList
required-type : hudson.node_monitors.DiskSpaceMonitor
converter-type : hudson.util.DescribableList$ConverterImpl
path : /hudson.util.DescribableList/hudson.node_monitors.DiskSpaceMonitor
line number : 12
version : not available
-------------------------------
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:79)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:134)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1061)
at hudson.util.XStream2.unmarshal(XStream2.java:113)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1045)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:925)
at hudson.XmlFile.read(XmlFile.java:142)
... 14 more
Caused by: java.lang.ClassCastException: hudson.node_monitors.DiskSpaceMonitor cannot be cast to hudson.util.DescribableList
at hudson.util.DescribableList$ConverterImpl.unmarshal(DescribableList.java:266)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
... 24 more