If so you are sure there is probably a conflict of JQuery objects in 1 SP form.
In this case SharePointBoost Cross-Site Lookup also uses a JQuery object to have their webpart function properly.
To solve the error conflict, you have to use the $.noConflict() method.
Just add an extra line :
$.noConflict(); jQuery(document).ready(function($) Code here ...
And you can start mixing JQuery Objects in 1 SharePoint form.