Cron PHP Code Fails to Run on Magento and Produces Error - php

Question

So I inherited a product reviews module. A cron runs every 6 hours. It checks for when to send an email out, but has not been working as of late.
Here's the config.xml file part containing the crontab. The crontab node is only placed within .
<crontab>
<jobs>
<company_reviews_delay>
<schedule>
<cron_expr>* * * * *</cron_expr><!-- every 6 hours -->
</schedule>
<run>
<model>reviews/adminhtml_observer::delaySend</model>
</run>
</company_reviews_delay>
</jobs>
</crontab>
The php file with the delaySend method is in Reviews/Model/Adminhtml/Observer.php
Here's the code for it
public function delaySend() {
$error_counter = 0;
$unsent_notifications = $this->getNotificationCollection()->addFieldToFilter('notified', array('lt' => 1));
foreach($unsent_notifications as $notification){
try{
$order = Mage::getModel('sales/order')->loadByIncrementId($notification->getOrderId());
if(!$this->getConfig()->isCronEnabled($order->getStoreId()) || !$this->getConfig()->isEnabled($order->getStoreId())){
continue; //skip for store that is disabled
}
$shipments_collection = $order->getShipmentsCollection();
if (empty($shipments_collection)) continue;
$shipment = $shipments_collection->getFirstItem();
}catch(Exception $e){
if($error_counter == 0){
mage::helper('mymodule_base')->logError('Review delay send error: ' . $e, true);
}
mage::helper('mymodule_base')->logError('Issue with notification order ID: ' . $notification->getOrderId(), false);
$error_counter++;
continue;
}
$execution_time = strtotime($shipment->getCreatedAt().'+'. $this->getConfig()->getCronDelay($order->getStoreId())); //e.g (+1 day to shipping date)
if($execution_time < time()){
$notification->sendEmail($order->getStoreId());
}
}
return $this;
}
I substituted a simple print "Hello"; command in the method and ran it on command line. Hello was printed out but we get this error:
2015-07-22T15:48:54+00:00 ERR (3): Warning: include(Symfony\Component\Console\Event\ConsoleTerminateEvent.php): failed to open stream: No such file or directory in /home/os2/public_html/lib/Varien/Autoload.php on line 94
2015-07-22T15:48:54+00:00 ERR (3): Warning: include(Symfony\Component\Console\Event\ConsoleTerminateEvent.php): failed to open stream: No such file or directory in /home/os2/public_html/lib/Varien/Autoload.php on line 94
2015-07-22T15:48:54+00:00 ERR (3): Warning: include(): Failed opening 'Symfony\Component\Console\Event\ConsoleTerminateEvent.php' for inclusion (include_path='/home/os2/public_html/app/code/local:/home/os2/public_html/app/code/community:/home/os2/public_html/app/code/core:/home/os2/public_html/lib:.:/usr/lib/php:/usr/local/lib/php') in /home/os2/public_html/lib/Varien/Autoload.php on line 94
Can anyone offer some advice or help? Thanks.