Bug with content profile on user registration page

Hi,

I'm using hierarchical select to select some taxonomy terms on a node_profile content type on user registration page.

When I try to create a new account, my content_profile successfully display, but, when I try to select some taxonomy terms using hierarchical select, I get some errors :

First, when I select a term I get the following error in a javascript popup :

Received an invalid response from the server

Then, if I refresh my page, I get an error message

warning: uasort() [function.uasort]: The argument should be an array in /drupal/d6/includes/common.inc on line 2843.

If I go to the content_profile creation form that is not embed in user registration (node/add/profile), the taxonomy selection with hierarchical select perfectly work.

Very strange issue isn't it ? I don't see what would alter HS in the user registration page...