error received when deleting filter subscription

This was our first time trying to use filters.. I created and shared a filter and showed a user how he could subscribe to it. And he did.
Then I had to recreate the filter so I deleted it (JIRA told me there were no subscriptions). And I recreated the filter with the same name as the previous filter. Then I had the user subscribe to this new filter. Although I wonder which filter it thinks he was subscribed to - the original or the second one. Anyway, I then decided to set up a subscription for a whole group to this filter, and this user is also a member of that group. So, on his screen he sees the original subscription, and I told him to delete the old (personal) one. However when he does, he gets this error (below). Notice the URL refers to filterid 10141 which is in factthe ID of the correct new filter. So I'm not sure if all that preamble was relevant or not. In my XML Backup from last night you can see the subscriptions:
<FilterSubscription id="10000" filterID="10140" username="markhandy" lastRun="2005-05-17 17:44:22.968" emailOnEmpty="true"/>
<FilterSubscription id="10001" filterID="10141" username="markhandy" lastRun="2005-05-17 17:34:08.921" emailOnEmpty="false"/>
Note that filterID 101040 no longer exists, and although I don't have an XML output for today yet, there will be additional subscriptions for filter 10141 for the group. I'll add that as a comment to the issue when I get it.

By the way - is there documentation on how to customize the e-mail (and which fields display) in the notification filter? I am sending out 'unassigned' issues, so having a column for "Assign To" doesn't make much sense.

System Error
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a description of your problem
cut & paste the error and system information found below
attach the application server log file
Cause:

Referer URL: http://issues.webfeat.com/secure/ViewSubscriptions.jspa?filterId=10141

Build Information:
Uptime: N/A
Edition: Enterprise
Version: 3.0.3
Build Number: 75

Server Information:
Application Server: Apache Tomcat/4.1.29
Servlet Version: 2.3

Memory Information:
Total Memory: 381 MB
Free Memory: 245 MB
Used Memory: 136 MB

System Information:
System Date: Wednesday, 18 May 2005
System Time: 11:35:51
Java Version: 1.5.0_01
Java Vendor: Sun Microsystems Inc.
JVM Version: 1.0
JVM Vendor: Sun Microsystems Inc.
JVM Implementation Version: 1.5.0_01-b08
Java Runtime: Java(TM) 2 Runtime Environment, Standard Edition
Java VM: Java HotSpot(TM) Client VM
User Name: gemini
User Timezone: America/New_York
User Locale: English (United States)
System Encoding: Cp1252
Operating System: Windows 2000 5.0
OS Architecture: x86
Application Server Container:
Database type: hsql
Database JNDI address: java:comp/env/jdbc/JiraDS

Request Information:
Request URL: http://issues.webfeat.com/secure/DeleteSubscription.jspa

• Scheme: http
• Server: issues.webfeat.com
• Port: 80
• URI: /500page.jsp
• - Context Path:
• - Servlet Path: /500page.jsp
• - Path Info: null
• - Query String: subId=10001&filterId=10141
  Request Attributes:
• javax.servlet.error.message : null<p><small><small><pre>java.lang.NullPointerException at com.atlassian.scheduler.OfBizJobStore.removeTrigger(OfBizJobStore.java:296) at org.quartz.core.QuartzScheduler.unscheduleJob(QuartzScheduler.java:587) at org.quartz.impl.StdScheduler.unscheduleJob(StdScheduler.java:251) at com.atlassian.jira.issue.subscription.DefaultSubscriptionManager.deleteSubscription(DefaultSubscriptionManager.java:123) at com.atlassian.jira.web.action.filter.FilterSubscription.doDelete(FilterSubscription.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:585) at webwork.action.ActionSupport.invokeCommand(ActionSupport.java:415) at webwork.action.ActionSupport.execute(ActionSupport.java:144) at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:46) at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131) at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:186) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:142) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:58) at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:168) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:181) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132) at com.atlassian.jira.web.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:25) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.ActionCleanupDelayFilter.doFilter(ActionCleanupDelayFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.gzip.GzipFilter.doFilter(GzipFilter.java:72) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549) at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666) at java.lang.Thread.run(Thread.java:595) </pre></small></small></p>
• os_securityfilter_already_filtered : true
• _sitemesh_using_stream : false
• com.atlassian.jira.web.filters.ActionCleanupDelayFilter : true
• com.atlassian.johnson.filters.JohnsonFilter_already_filtered : true
• javax.servlet.error.request_uri : /secure/DeleteSubscription.jspa
• jira.webwork.generic.dispatcher : webwork.dispatcher.GenericDispatcher@1672c01
• javax.servlet.error.status_code : 500
• _sitemesh_filterapplied : true
• jira.webwork.cleanup : false
• javax.servlet.error.servlet_name : action
• com.atlassian.jira.web.filters.gzip.GzipFilter_already_filtered : true
• loginfilter.already.filtered : true
• atlassian.core.seraph.original.url : /secure/DeleteSubscription.jspa?subId=10001&filterId=10141
• webwork.result : Value stack =========== ===========

Request Logging:
0 log statements generated by this request: