Contribution receipt not being sent after paying with Paypal

Using Joomla3.4.8 and CiviCRM 4.7.2, a receipt is not being sent when using the Paypal option but is being sent when using the Pay later option. Replicating on demo site is not an option.

This is an issue on 2 totally separate Joomla stes and also recorded by others e.g. http://civicrm.stackexchange.com/questions/7794/contribution-receipt-not-being-sent-after-paying-with-paypal/10456#

Backtrace shows the sequence of events
Mar 15 21:31:45 [info] Contribution record updated successfully

Mar 15 21:31:45 [info] $Fatal Error Details = Array
(
[message] => The requested Profile (gid=4) is disabled OR it is not configured to be used for 'Profile' listings in its Settings OR there is no Profile with that ID OR you do not have permission to access this profile. Please contact the site administrator if you need assistance.
[code] =>
)

Mar 15 21:31:45 [info] $backTrace = #0 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Core/Error.php(366): CRM_Core_Error::backtrace("backTrace", TRUE)
#1 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Core/BAO/UFGroup.php(368): CRM_Core_Error::fatal("The requested Profile (gid=4) is disabled OR it is not configured to be used ...")
#2 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Event/BAO/Event.php(1295): CRM_Core_BAO_UFGroup::getFields(4, FALSE, 4, NULL, NULL, FALSE, NULL, FALSE, NULL, 4, "field_name", TRUE)
#3 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Event/BAO/Event.php(1136): CRM_Event_BAO_Event::buildCustomDisplay("4", "customPre", "2790", Object(CRM_Core_Smarty), "149", "0", NULL, (Array:0))
#4 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Contribute/BAO/Contribution.php(2463): CRM_Event_BAO_Event::sendMail("2790", (Array:13), "149", "0", FALSE)
#5 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Contribute/BAO/Contribution.php(4594): CRM_Contribute_BAO_Contribution->composeMessageArray((Array:30), (Array:8), (Array:13), FALSE, FALSE)
#6 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Contribute/BAO/Contribution.php(4548): CRM_Contribute_BAO_Contribution::sendMail((Array:30), (Array:8), Object(CRM_Contribute_BAO_Contribution), (Array:13), FALSE, FALSE)
#7 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Core/Payment/BaseIPN.php(449): CRM_Contribute_BAO_Contribution::completeOrder((Array:30), (Array:8), (Array:8), Object(CRM_Core_Transaction), FALSE, Object(CRM_Contribute_BAO_Contribution), FALSE, FALSE)
#8 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Core/Payment/PayPalIPN.php(290): CRM_Core_Payment_BaseIPN->completeTransaction((Array:30), (Array:8), (Array:8), Object(CRM_Core_Transaction), FALSE)
#9 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/CRM/Core/Payment/PayPalIPN.php(347): CRM_Core_Payment_PayPalIPN->single((Array:30), (Array:8), (Array:8), FALSE, FALSE)
#10 /home/lcct/public_html/administrator/components/com_civicrm/civicrm/extern/ipn.php(55): CRM_Core_Payment_PayPalIPN->main()
#11