Null-pointers related to user access in EACJ

I'm seeing a lot of the following in the logs for EACJ:

2007-08-15 21:29:54,266 resin-tcp-connection-j2ee.extranet.atlassian.com-jira:6802-29 ERROR [action.admin.user.UserPickerBrowser] Exception getting users: java.lang.NullPointerException
java.lang.NullPointerException
at com.opensymphony.user.User.<init>(User.java:53)
at com.opensymphony.user.UserManager.buildEntity(UserManager.java:339)
at com.opensymphony.user.UserManager.getEntities(UserManager.java:290)
at com.opensymphony.user.UserManager.getUsers(UserManager.java:200)
at com.atlassian.core.user.UserUtils.getAllUsers(UserUtils.java:65)
at com.atlassian.jira.web.bean.UserPickerFilter.getFilteredUsers(UserPickerFilter.java:67)
at com.atlassian.jira.web.action.admin.user.UserPickerBrowser.getBrowsableItems(UserPickerBrowser.java:107)
at com.atlassian.jira.web.action.admin.user.UserPickerBrowser.getUsers(UserPickerBrowser.java:129)
at jrockit.reflect.VirtualNativeMethodInvoker.invoke(Ljava.lang.Object;[Ljava.lang.Object;)Ljava.lang.Object;(Unknown Source)
at java.lang.reflect.Method.invoke(Ljava.lang.Object;[Ljava.lang.Object;I)Ljava.lang.Object;(Unknown Source)
at webwork.util.InjectionUtils$DefaultInjectionImpl.invoke(InjectionUtils.java:61)
at webwork.util.InjectionUtils.invoke(InjectionUtils.java:52)
at webwork.util.ValueStack.findValue(ValueStack.java:186)
at webwork.util.ValueStack.findValue(ValueStack.java:175)
at webwork.view.taglib.WebWorkBodyTagSupport.findValue(WebWorkBodyTagSupport.java:61)
at com.atlassian.jira.web.tags.TextTag.doEndTag(TextTag.java:149)
at jsp._secure._popups._userpickerjsp._jspService(_userpicker_jsp.java:146)
at com.caucho.jsp.JavaPage.service(JavaPage.java:60)
at com.caucho.jsp.Page.pageservice(Page.java:579)
at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:175)
at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:115)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:277)
at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:106)
at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:279)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
at com.atlassian.jira.web.filters.AccessLogFilter.doFilter(AccessLogFilter.java:73)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:38)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)

2007-08-15 21:29:54,299 JiraQuartzScheduler_Worker-0 ERROR [service.util.handler.CreateIssueHandler] Could not create issue!
java.lang.NullPointerException
at com.opensymphony.user.User.<init>(User.java:53)
at com.opensymphony.user.UserManager.buildEntity(UserManager.java:339)
at com.opensymphony.user.UserManager.getEntities(UserManager.java:290)
at com.opensymphony.user.UserManager.getUsers(UserManager.java:200)
at com.atlassian.core.user.UserUtils.getAllUsers(UserUtils.java:65)
at com.atlassian.jira.service.util.handler.AbstractMessageHandler.findUserByEmail(AbstractMessageHandler.java:539)
at com.atlassian.jira.service.util.handler.AbstractMessageHandler.getAuthorFromSender(AbstractMessageHandler.java:493)
at com.atlassian.jira.service.util.handler.AbstractMessageHandler.getReporter(AbstractMessageHandler.java:460)
at com.atlassian.jira.service.util.handler.CreateIssueHandler.handleMessage(CreateIssueHandler.java:91)
at com.atlassian.jira.service.util.handler.CreateOrCommentHandler.handleMessage(CreateOrCommentHandler.java:115)
at com.atlassian.jira.service.services.mail.MailFetcherService.run(MailFetcherService.java:190)
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)

I'm not seeing any corresponding errors in the crowd logs.