error when uploading file within standalone form

I am getting the following error in contact forms. If i do a reload then the form is sent and the file uploaded. this i hapenning even when files are not beeing uploaded but the field is present in the contact form.

here is the backtrace at the demo site:

<<
/home/demo.civicrm.org/svn/stable/CRM/Core/Error.php, backtrace, 148

, handle,
/home/demo.civicrm.org/svn/stable/packages/PEAR.php, call_user_func, 901

/home/demo.civicrm.org/svn/stable/packages/HTML/QuickForm.php, PEAR_Error, 1988
/home/demo.civicrm.org/svn/stable/packages/PEAR.php, HTML_QuickForm_Error, 563
/home/demo.civicrm.org/svn/stable/packages/HTML/QuickForm.php, raiseError, 748

/home/demo.civicrm.org/svn/stable/CRM/Core/QuickForm/Action/Upload.php, getElement, 86
/home/demo.civicrm.org/svn/stable/CRM/Core/QuickForm/Action/Upload.php, upload, 131
/home/demo.civicrm.org/svn/stable/packages/HTML/QuickForm/Controller.php, perform, 195

/home/demo.civicrm.org/svn/stable/packages/HTML/QuickForm/Page.php, handle, 95
/home/demo.civicrm.org/svn/stable/CRM/Core/Controller.php, handle, 173
/home/demo.civicrm.org/svn/stable/CRM/Utils/Wrapper.php, run, 72

/home/demo.civicrm.org/svn/stable/CRM/Core/Invoke.php, run, 693
/home/demo.civicrm.org/svn/stable/CRM/Core/Invoke.php, profile, 112
/home/demo.civicrm.org/svn/stable/drupal/civicrm.module, invoke, 290
, civicrm_invoke,

/home/demo.civicrm.org/public/drupal/includes/menu.inc, call_user_func_array, 418
/home/demo.civicrm.org/public/drupal/index.php, menu_execute_active_handler, 15
>>

and the error message:

<<

Array
(
[callback] => Array
(
[0] => CRM_Core_Error
[1] => handle
)

[code] => -3
[message] => QuickForm Error: nonexistent html element

[mode] => 16
[debug_info] => Element 'uploadFile' does not exist in HTML_QuickForm::getElement()
[type] => HTML_QuickForm_Error
[user_info] => Element 'uploadFile' does not exist in HTML_QuickForm::getElement()

[to_string] => [html_quickform_error: message="nonexistent html element" code=-3 mode=callback callback=CRM_Core_Error::handle prefix="QuickForm Error: " info="Element 'uploadFile' does not exist in HTML_QuickForm::getElement()"]

)

>>

I created a profile named:
testing file upload and pasted the form source in a page of a drupal site.

by the way i use drupal 4.7, civicrm 1.6 php 4