Exception systematically thrown systematically when a job is fired

2009-05-25 01:39:00,026 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-1] ERROR core.JobRunShell                - Job DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an unhandled Exception:  
java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
2009-05-25 01:39:00,030 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-1] ERROR core.ErrorLogger                - Job (DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an exception. 
org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NoSuchFieldError: ROLE]
	at org.quartz.core.JobRunShell.run(JobRunShell.java:213)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
Caused by: java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	... 1 more
2009-05-25 01:39:00,031 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-1] ERROR scheduler.StatusListener        - Job (DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an exception. 
org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NoSuchFieldError: ROLE]
	at org.quartz.core.JobRunShell.run(JobRunShell.java:213)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
Caused by: java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	... 1 more
2009-05-25 01:40:00,015 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-2] ERROR core.JobRunShell                - Job DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an unhandled Exception:  
java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
2009-05-25 01:40:00,016 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-2] ERROR core.ErrorLogger                - Job (DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an exception. 
org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NoSuchFieldError: ROLE]
	at org.quartz.core.JobRunShell.run(JobRunShell.java:213)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
Caused by: java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	... 1 more
2009-05-25 01:40:00,017 [http://localhost:8080/xwiki/bin/view/Main/WebHome] [DefaultQuartzScheduler_Worker-2] ERROR scheduler.StatusListener        - Job (DEFAULT.xwiki:Scheduler.WatchListJob1_0 threw an exception. 
org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NoSuchFieldError: ROLE]
	at org.quartz.core.JobRunShell.run(JobRunShell.java:213)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529)
Caused by: java.lang.NoSuchFieldError: ROLE
	at com.xpn.xwiki.plugin.scheduler.AbstractJob.execute(AbstractJob.java:60)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	... 1 more