Can't rename a folder

I'm trying to rename a folder with
   RenameFile( old_name, new_name );

But it's throwing an error 32 (file/folder already in use).
I checked both paths and are correct.

I suspect the error comes from a TOpenDialog.
This TOpenDialog asks the user to open a file:

        openDialog:= TOpenDialog.Create( nil );
	openDialog.InitialDir	:= Dir + 'projects';
	openDialog.Filter	:= 'XML files|*.xml|All files|*.*';
	openDialog.Title		:= 'Select a file project';
	openDialog.Options	:= [ofReadOnly];
	//Display openDialog
	if openDialog.Execute then
		load_project_info( openDialog.FileName )
	openDialog.free;

This works ok, but after that I'm not able to modify any file/folder
element inside folder selected by user.

load_project_info loads some data from file selected, but this is not
the problem 'cause I try to comment this line and the error persists.

I'm not able to change folder's name not even from windows explorer
(after using TOpenDialog); when my program exits then I can.