zend.ze1_compatibility_mode error

Hi,
I have some phprunner applications created with earlier versions (i think version 4) which have run trouble free for years up until recently. Something has caused the following error to appear upon login in one of my programs at /login.php?. Newer versions of my programs are not affected.
Error 2048

Implicit cloning object of class 'Smarty' because of 'zend.ze1_compatibility_mode'
If there is a quick fix for this please advise. I no longer have the project files for these early programs but I still need them to run.
thank you