"Snippet type is unrecognized" when viewing contact record

when trying to view the contacts summary page, the error "Snippet type is unrecognized" is displayed in the usual yellow strip accross the screen.

I can't see any differences between this contact and any other contacts (which do display) (apart from the obvious).

ConfigAndLog doesn't provide much of use (for me - sorry):

_Apr 01 11:12:09 [info] $Fatal Error Details = Array
(
[message] => Snippet type is unrecognized
[code] =>
)

Apr 01 11:12:09 [info] $backTrace = #0 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Error.php(364): CRM_Core_Error::backtrace("backTrace", TRUE)
#1 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Region.php(223): CRM_Core_Error::fatal("Snippet type is unrecognized")
#2 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Smarty/plugins/block.crmRegion.php(26): CRM_Core_Region->render(" <div class=\"crm-summary-contactinfo-block\">\n ...", TRUE)
#3 /var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%12/12B/12B53F83%%Summary.tpl.php(182): smarty_block_crmRegion((Array:1), " <div class=\"crm-summary-contactinfo-block\">\n ...", Object(CRM_Core_Smarty), FALSE)
#4 /var/www/drupal743civi4610/sites/all/modules/civicrm/packages/Smarty/Smarty.class.php(1907): include("/var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%12/12B/...")
#5 /var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%0C/0CB/0CBEC124%%default.tpl.php(19): Smarty->_smarty_include((Array:2))
#6 /var/www/drupal743civi4610/sites/all/modules/civicrm/packages/Smarty/Smarty.class.php(1907): include("/var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%0C/0CB/...")
#7 /var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%06/069/0693F89E%%drupal.tpl.php(64): Smarty->_smarty_include((Array:2))
#8 /var/www/drupal743civi4610/sites/all/modules/civicrm/packages/Smarty/Smarty.class.php(1264): include("/var/sites/praxisunico.org.uk/files/civicrm/templates_c/en_US/en_GB/%%06/069/...")
#9 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Smarty.php(203): Smarty->fetch("CRM/common/drupal.tpl", NULL, NULL, FALSE)
#10 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Page.php(233): CRM_Core_Smarty->fetch("CRM/common/drupal.tpl")
#11 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Contact/Page/View/Summary.php(103): CRM_Core_Page->run()
#12 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Invoke.php(312): CRM_Contact_Page_View_Summary->run((Array:3), NULL)
#13 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Invoke.php(86): CRM_Core_Invoke::runItem((Array:14))
#14 /var/www/drupal743civi4610/sites/all/modules/civicrm/CRM/Core/Invoke.php(54): CRM_Core_Invoke::_invoke((Array:3))
#15 /var/www/drupal743civi4610/sites/all/modules/civicrm/drupal/civicrm.module(489): CRM_Core_Invoke::invoke((Array:3))
#16 [internal function](): civicrm_invoke("contact", "view")
#17 /var/www/drupal743civi4610/includes/menu.inc(527): call_user_func_array("civicrm_invoke", (Array:2))
#18 /var/www/drupal743civi4610/index.php(21): menu_execute_active_handler()
#19

_
Anyone know what this may relate to or where to look for clues?

Thanks.