[support] Problem with fcgid, suexec and multisite Drupal6 sites

Hi, for security reasons, I'm trying to migrate some Drupal sites from apache mod_php to cgi-php, with fcgid and suexec. This works well for normal sites and multisite Drupal7 installations. It' not working for a multisite Drupal6 installation, I get the installer instead of the actual site. Any ideas what could be wrong? regards Rolf