Registration redirect to /Array

After registration a user is beeing redirected to /Array when using "Dialog Api" Module for opening registration in a popup.

Log:

Typ PHP
Date Samstag, Februar 12, 2011 - 20:43
User Anonymous
Standort http://www.xxxxxxxxx.com/user/register/ajax
Referrer http://www.xxxxxxxe.com/
Nachricht Warning: Illegal offset type in _drupal_lookup_path_direct() (line 115 of /var/www/xxxxxx/includes/path.inc).
Schweregrad Fehler
Hostname xxxxxx
Operationen
Server IP xxxxx
Server Name xxxxx

I now that this maybe caused by another module, so i expect no digging into it. Only wanted it to park here if someone maybe has the same problem.