white page after upgrade

[iown]

Hi after upgrading to 1.4 my backend is working fine but I recieve this error in the frontend for most but not all pages.
Notice: function call 'register_function' is unknown or deprecated. in /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/sysplugins/smarty_internal_wrapper.php on line 57

Fatal error: Uncaught exception 'Exception' with message 'Plugin tag "dateFormat" already registered' in /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/sysplugins/smarty_internal_register.php:34 Stack trace: #0 /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/Smarty.class.php(776): Smarty_Internal_Register->registerPlugin('function', 'dateFormat', Array) #1 [internal function]: Smarty->__call(Array, Array) #2 /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/sysplugins/smarty_internal_wrapper.php(77): Smarty->registerPlugin('registerPlugin', Array) #3 /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/Smarty.class.php(766): Smarty_Internal_Wrapper->convert('function', 'dateFormat', Array) #4 /home/newmobil/public_html/thorweldingsupplies.com.au/init.php(100): Smarty->__call(Array, Array) #5 /home/newmobil/public_html/thorweldingsupplies.com.au/init.php(100): Smarty->register_function('register_functi...', Array) #6 /home/newmobil/public_html/thorweldin in /home/newmobil/public_html/thorweldingsupplies.com.au/tools/smarty/sysplugins/smarty_internal_register.php on line 34

Can anyone help please?
Many thanks Keith