"some kind of server/host setting" isn't very useful. Can you be more specific about what you found (what was suggested)? If no one here on LunarForums can help, be sure to read/post on WordPress-specific discussion groups.
Has this WP installation been running OK, and then just suddenly started giving errors? LP has started upgrading servers to PHP 5.4, so maybe your WP code is old and incompatible with PHP 5.4. An immediate upgrade to the latest WP may be in order. If this is already current WP or is a new installation, and has never worked, it could be a configuration problem. In any case, we would need more specific information on what has been suggested you try.