Hi Louis,
check the following settings:
pcre.backtrack_limit | pcre.recursion_limit
width php version < 5.3.7 was the default value 100k
>= 5.3.7 it's the default 1M
pcre.backtrack_limit sets the maximum bind length PREG calls (e.g. preg_replace_callback) can make. However the actual maximum seems to be approximately half the value set here, possibly due to the character encoding that PCRE runs with internally
It is limited by RAM size, not the ulimit on stack-size.
e.g.
pcre.backtrack_limit 10000000
pcre.recursion_limit 500000
max_input_time
the default value is 30 seconds set it to 60 or 120
e.g.
max_input_time 120
change suhosin configuration (if the server suhosin used can to it in .htaccess file)
e.g.
php_value suhosin.post.max_array_index_length 512
php_value suhosin.post.max_name_length 512
php_value suhosin.post.max_vars 5000
php_value suhosin.request.max_vars 5000
php_value suhosin.request.max_array_index_length 512
Regards
paulbr