Why is “/page/2/” not working?

Finally got pagination to work with the below code, but now the pagination links to /videos/page/2/, which doesn’t exist. How do I get page 2 to work?

<?php
$temp = $wp_query;
$wp_query= null;
$wp_query = new WP_Query();
$wp_query->query('post_type=videos&showposts=1'.'&paged='.$paged);

while ($wp_query->have_posts()) : $wp_query->the_post();
  //display stuff
endwhile;           

php  wp_pagenavi();
 ?>