In the same way that the filefield module did not work the nodereference and usereference modules do not work.

http://drupal.org/node/898366

Basically if we allow for more that one node or user reference, and only fill one out in the node edit form, but leave the second one in the list blank it says the field is empty. If I have two blank spaces for nodererence, and only put one in, the second empty spot gives the error.

Thanks!