Recovering from a WSOD related to hierarchical select module
The _hierarchical_select_setup_js() function is defined in the hierarchical_select.module so this is one of those "it should work" situations.  Since it isn't, a quick workaround would be to copy it out of there and into, oh, say, your template.php file, wrapped in a "if !function_exists()" so it doesn't WSOD when it does :)