TOPIC: DT Register and PayPal Issue

Here is my setup

Joomla 2.5.9
DT Register 2.7.17

My site used to work fine and for some reason now when registering for an event I get an error. My site works fine, Paypal processes the payment and the redirect back to my site fails and DT register doesn't recognize that a payment has been processed, i.e. no DT conformation code.

components/com_dtregister/success.php?return=151&Itemid=270&task=notification
[an error occurred while processing this directive]

Has anybody come across this error. Any help would be appreciated.