I seem to have exhausted all the references on this subject, but if this is a duplicate post my apologies.

I am having a problem where ANY custom post page displays the 404.php file's error content, regardless of method of getting there. This includes simply going to something as rudimentary as http://domain.com/?p=123.

I have done the following:

 - Flushed permalink settings (though I don't think it's a permalink problem)
 - Deleted .htaccess and recreated it by going to settings -> permalinks
 - Specifically created a single-[name].php file for any given type
 - Disabled all plugins
 - Checked for any page/taxonomy name conflicts (still fails even w/ random name)
 - Checked server logs for errors (none since troubleshooting began)
 - Uploaded entire theme to different WP install

All to no avail.

I have reduced the custom post registration to as simple a function as I can conjure:

    add_action('init', 'init_sample');
    function init_sample() {
    	$args = array(
    		'public' => true,
    	);
    	register_post_type( 'sample' , $args );
    }

But neither this nor any other combinations of arguments seem to help.

Even clicking the "View Post" link in admin takes one to a 404 page.

I can, however, retrieve custom posts via query with no problem.

I'm running WP v3.2.1.

If I had to guess, I'd say there's something elsewhere in the theme fouling things up, but I have no idea where to go to find that out - could anyone provide some suggestions on where to even look to troubleshoot this issue?