Moving an old EE 2.5.5 site to a server with PHP 5.4 instead of the old 5.3, I have run into this error, and can't see how to fix it:
A PHP Error was encountered Severity: 8192 Message: Non-static method Comment::form() should not be called statically, assuming $this from incompatible context Filename: libraries/Template.php Line Number: 3004
Line 3004 is:
$str = str_replace($match[$i], Comment::form(TRUE, $this->EE->functions->cached_captcha), $str);
Sadly, upgrading EE is not an option at the moment.