Same behavior on my WP website. The problem is that my PHP 5.3.10 version doesn’t parses the ‘[‘ array statement (php -l ./lib/Plugin.php)
Validation on another server with PHP 5.5 shows no errors.
Renaming the portfolio plugin directory and restarting webserver gets the website online again. No slides shows of cause as the plugin is not loaded.
The back port to PHP 5.3 is not working, at least for my version which comes with Ubuntu 12.04.5 LTS. This version is out there a lot I guess, so fixing the plugin makes sense in stead of upgrading PHP by hand…
Regards,
Ferry