Spring container 2.5.3 running for months, with a SimpleTriggerBean set to execute every 5 minutes. Suddenly stops working.

I see the next fire time was long since passed (over 12 hours), previous fire time also, and the mayFireAgain == true. I shutdown the Spring container, and everything ran normally.

Any ideas?

My config is below.
-------------------
<bean
id="FTPTrigger"
class="org.springframework.scheduling.quartz.Simpl eTriggerBean"
>
<property
name="jobDetail"
ref="FTPjobDetail" />
<!-- delay milliseconds -->
<property
name="startDelay"
value="10" />
<!-- repeat every X milliseconds -->
<property
name="repeatInterval"
value="300000" />
</bean>