Starting multiple applications on one machine leads to potential failure of startup

This is what happend when starting 10 instances of viewerproxy - 1 failed. Same error seen on harvester-machine with 6 harvester-instances. Seems they want to read the settings-files all at once? A simple restart of failed applications makes them start just normally.
Starting dk.netarkivet.viewerproxy.ViewerProxy
Version: 3.8.0 status RELEASE
dk.netarkivet.viewerproxy.ViewerProxy Running
Could not start class dk.netarkivet.viewerproxy.ViewerProxy
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.ApplicationUtils.startApp(ApplicationUtils.java:155)
at dk.netarkivet.viewerproxy.ViewerProxyApplication.main(ViewerProxyApplication.java:40)
Caused by: dk.netarkivet.common.exceptions.ArgumentNotValid: Error creating singleton of class 'dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient':
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:101)
at dk.netarkivet.common.distribute.arcrepository.ArcRepositoryClientFactory.getViewerInstance(ArcRepositoryClientFactory.java:58)
at dk.netarkivet.viewerproxy.ViewerProxy.<init>(ViewerProxy.java:71)
at dk.netarkivet.viewerproxy.ViewerProxy.getInstance(ViewerProxy.java:93)
... 6 more
Caused by: java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1010)
at dk.netarkivet.common.utils.Settings.get(Settings.java:149)
at dk.netarkivet.common.utils.Settings.getLong(Settings.java:193)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.<init>(JMSArcRepositoryClient.java:137)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.getInstance(JMSArcRepositoryClient.java:157)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:99)
... 9 more
Jun 25 2009 3:36:55 PM dk.netarkivet.common.utils.ApplicationUtils logExceptionAndPrint
SEVERE: Could not start class dk.netarkivet.viewerproxy.ViewerProxy
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.ApplicationUtils.startApp(ApplicationUtils.java:155)
at dk.netarkivet.viewerproxy.ViewerProxyApplication.main(ViewerProxyApplication.java:40)
Caused by: dk.netarkivet.common.exceptions.ArgumentNotValid: Error creating singleton of class 'dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient':
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:101)
at dk.netarkivet.common.distribute.arcrepository.ArcRepositoryClientFactory.getViewerInstance(ArcRepositoryClientFactory.java:58)
at dk.netarkivet.viewerproxy.ViewerProxy.<init>(ViewerProxy.java:71)
at dk.netarkivet.viewerproxy.ViewerProxy.getInstance(ViewerProxy.java:93)
... 6 more
Caused by: java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1010)
at dk.netarkivet.common.utils.Settings.get(Settings.java:149)
at dk.netarkivet.common.utils.Settings.getLong(Settings.java:193)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.<init>(JMSArcRepositoryClient.java:137)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.getInstance(JMSArcRepositoryClient.java:157)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:99)
... 9 more
Jun 25 2009 3:36:56 PM dk.netarkivet.common.utils.EMailNotifications errorEvent
SEVERE: Mailing netarkivet error: Could not start class dk.netarkivet.viewerproxy.ViewerProxy
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.ApplicationUtils.startApp(ApplicationUtils.java:155)
at dk.netarkivet.viewerproxy.ViewerProxyApplication.main(ViewerProxyApplication.java:40)
Caused by: dk.netarkivet.common.exceptions.ArgumentNotValid: Error creating singleton of class 'dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient':
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:101)
at dk.netarkivet.common.distribute.arcrepository.ArcRepositoryClientFactory.getViewerInstance(ArcRepositoryClientFactory.java:58)
at dk.netarkivet.viewerproxy.ViewerProxy.<init>(ViewerProxy.java:71)
at dk.netarkivet.viewerproxy.ViewerProxy.getInstance(ViewerProxy.java:93)
... 6 more
Caused by: java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1010)
at dk.netarkivet.common.utils.Settings.get(Settings.java:149)
at dk.netarkivet.common.utils.Settings.getLong(Settings.java:193)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.<init>(JMSArcRepositoryClient.java:137)
at dk.netarkivet.archive.arcrepository.distribute.JMSArcRepositoryClient.getInstance(JMSArcRepositoryClient.java:157)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:99)
... 9 more
Exception in thread "Monitor-registry-client" dk.netarkivet.common.exceptions.ArgumentNotValid: Error creating singleton of class 'dk.netarkivet.common.distribute.JMSConnectionSunMQ':
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:101)
at dk.netarkivet.common.distribute.JMSConnectionFactory.getInstance(JMSConnectionFactory.java:37)
at dk.netarkivet.monitor.distribute.JMSMonitorRegistryClient$1.run(JMSMonitorRegistryClient.java:103)
Cleaning up dk.netarkivet.monitor.distribute.JMSMonitorRegistryClient
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)
Caused by: java.lang.IllegalStateException: Shutdown in progress
at java.lang.ApplicationShutdownHooks.add(ApplicationShutdownHooks.java:39)
at java.lang.Runtime.addShutdownHook(Runtime.java:192)
at dk.netarkivet.common.distribute.JMSConnection.initConnection(JMSConnection.java:175)
at dk.netarkivet.common.distribute.JMSConnectionSunMQ.<init>(JMSConnectionSunMQ.java:113)
at dk.netarkivet.common.distribute.JMSConnectionSunMQ.getInstance(JMSConnectionSunMQ.java:125)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at dk.netarkivet.common.utils.SettingsFactory.getInstance(SettingsFactory.java:99)
... 4 more
Cleaned up dk.netarkivet.monitor.distribute.JMSMonitorRegistryClient