por Ken Task.
Indicates that the version of PHP (as provided on bluehost) not compatible with code that is in Moodle 2.3.1.
Please see the following:
Does Bluehost offer PHP 5.3.x? If so, find out how to point Moodle to use that version of PHP rather then PHP 5.4.x from hosting provider.
Consider upgrading the Moodle to 2.3.2 as there might have been a fix in Moodle code as well.
'spirit of sharing', Ken