Using the autocomplete field for a cck nodereference always displays the node id as a cryptic bracketed extension:
Page Title [nid:23]
I unders
To anyone coming across this (rather old) topic by way of a google search - for Drupal 7 please consider using entityreference module and "Entity Reference" field type if possible.
You can acheive a lot more in configuration with an "Entity Reference" field. It doesn't have this problem with the nid in square brackets.