I'm creating a shopping site using PHP5 and I keep getting the following error when testing the site on my local machine:

The site seems to be working fine at that point, even with the error on. However, if I implement a file called 'tss_error_handler.php', I get the following error:

This time the site doesn't work at all and only the above error code is displayed.
I assumed this was an error in my version of Smarty, so I installed several different versions but the error still persists. Any idea what's wrong?