CodeIgniter: “The filetype you are attempting to upload is not allowed.”

[eluser]rickster[/eluser]
I seem to have the same problem. On a hosting account with only doc, pdf and docx allowed.
pdf uploads fine but the doc and docx I got 'not allowed'. mime-types are setup and correct, this really has me stumped.

Code:

$config['upload_path'] = $_SERVER['DOCUMENT_ROOT'] . '/uploads/';
  $config['allowed_types'] = 'doc|pdf|docx';
  $config['max_size'] = '200';
  $this->load->library('upload', $config);
  $this->upload->do_upload();

Any more suggestions are most welcome.