ExceptionInInitializerError executing PopService

My POP e-mail checking isn't working whereas it was previously. I'm not aware of any changes I made that would be related. Here are the errors in the logs:

2007-07-26 08:52:10,953 JiraQuartzScheduler_Worker-1 ERROR [atlassian.jira.service.ServiceRunner] Error occured while executing the service [ Container: com.atlassian.jira.service.services.pop.PopService delay [60000ms]]
java.lang.ExceptionInInitializerError
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:131)
at com.atlassian.jira.service.JiraServiceContainerImpl.run(JiraServiceContainerImpl.java:67)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:61)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)
Caused by: java.util.ConcurrentModificationException
at java.util.Hashtable$Enumerator.next(Unknown Source)
at java.util.Hashtable.putAll(Unknown Source)
at com.atlassian.mail.config.PropertiesLoader.<clinit>(PropertiesLoader.java:29)
... 5 more
2007-07-26 08:52:11,625 main WARN [webwork.dispatcher.ServletDispatcher] Unable to find 'webwork.multipart.saveDir' property setting. Defaulting to javax.servlet.context.tempdir
2007-07-26 08:54:10,750 JiraQuartzScheduler_Worker-3 ERROR [atlassian.jira.service.ServiceRunner] Error occured while executing the service [ Container: com.atlassian.jira.service.services.pop.PopService delay [60000ms]]
java.lang.NoClassDefFoundError: Could not initialize class com.atlassian.mail.config.PropertiesLoader
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:131)
at com.atlassian.jira.service.JiraServiceContainerImpl.run(JiraServiceContainerImpl.java:67)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:61)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)
2007-07-26 08:55:10,750 JiraQuartzScheduler_Worker-3 ERROR [atlassian.jira.service.ServiceRunner] Error occured while executing the service [ Container: com.atlassian.jira.service.services.pop.PopService delay [60000ms]]
java.lang.NoClassDefFoundError: Could not initialize class com.atlassian.mail.config.PropertiesLoader
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:131)
at com.atlassian.jira.service.JiraServiceContainerImpl.run(JiraServiceContainerImpl.java:67)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:61)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)
2007-07-26 08:56:10,750 JiraQuartzScheduler_Worker-3 ERROR [atlassian.jira.service.ServiceRunner] Error occured while executing the service [ Container: com.atlassian.jira.service.services.pop.PopService delay [60000ms]]
java.lang.NoClassDefFoundError: Could not initialize class com.atlassian.mail.config.PropertiesLoader
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:131)
at com.atlassian.jira.service.JiraServiceContainerImpl.run(JiraServiceContainerImpl.java:67)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:61)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)
2007-07-26 08:57:10,750 JiraQuartzScheduler_Worker-3 ERROR [atlassian.jira.service.ServiceRunner] Error occured while executing the service [ Container: com.atlassian.jira.service.services.pop.PopService delay [60000ms]]
java.lang.NoClassDefFoundError: Could not initialize class com.atlassian.mail.config.PropertiesLoader
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:131)
at com.atlassian.jira.service.JiraServiceContainerImpl.run(JiraServiceContainerImpl.java:67)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:61)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)