Test execution unexpectedly aborted with Shutdown hook

Hi,
I am trying to run a load test, on CentOS 6.4, on non-GUI mode.

The test plan is supposed to run for 12 hours, but it is stopping at random intervals (I have reproduced it 5 times so far, and each time at a different progress level in the test).

The only thing I have found so far to help me investigate is in the jmeter.log file, at the end, I see the following lines:

2014/03/19 08:38:43 INFO - jmeter.reporters.ResultCollector: Shutdown hook started
2014/03/19 08:38:43 INFO - jmeter.reporters.ResultCollector: Shutdown hook ended

I have not done anything in my test plan to stop the test execution programmatically, and I don't think any user has tried to stop the test execution manually either.

The same test plan, used in non-GUI mode under Windows is running all the way through the 12 hours.

Any hint on specific items that I could be looking at would be very much appreciated.

For information, the thread group definition of my test plan looks like this:

<ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group1" enabled="true">
<stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
<elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
<boolProp name="LoopController.continue_forever">false</boolProp>
<intProp name="LoopController.loops">-1</intProp>
</elementProp>
<stringProp name="ThreadGroup.num_threads">100</stringProp>
<stringProp name="ThreadGroup.ramp_time">10</stringProp>
<longProp name="ThreadGroup.start_time">1394045493000</longProp>
<longProp name="ThreadGroup.end_time">1394045493000</longProp>
<boolProp name="ThreadGroup.scheduler">true</boolProp>
<stringProp name="ThreadGroup.duration">43200</stringProp>
<stringProp name="ThreadGroup.delay">0</stringProp>
</ThreadGroup>

Thanks,
Ramiro