Fckeditor doesn't work in Drupal

When installing the fckeditor module in Drupal on some host configurations, probably centos and Apache, this error may occur when browsing for files.

The server didn't reply with a proper XML data. Please check your configuration.

The clue to this error, at least on centos, is in /usr/local/apache/logs/error_log:

[Tue Mar 16 21:20:06 2010] [error] [client xxx.xxx.xxx.xxx] SoftException in Application.cpp:601: Directory "/xx/xx/xx/xx/sites/default/modules/fckeditor/fckeditor/editor/filemanager" is writeable by group