there was a change in how excerpts are handles in 3.5.3 - the code was changed from using a php 'explode()' to a php 'preg_split()'. I'm wondering if the preg_split is causing the issue.

With this in mind I have a test for you to run.
1) download the attached file, unzip it
2) edit the file (USING A TEXT EDITOR) and change the text 'this is a string' to something with french characters - make sure to keep the single quotes around it
3) save it and upload it to the atahualpa folder
4) create a new page called 'test'
5) assign the template 'pmwtest' to the page
6) publish the page - you can make it private, just note the url
7) view the page and see if there is any difference in the two tests - send me the url so I can look also.
Attachment 1000

My blogue is in the intranet. I can not give you the link.

I have the error when i want to see the new page.

Fatal error: Cannot redeclare bfa_get_options() (previously declared in D:\www\blog\wp-content\themes\atahualpa\functions\bfa_get_options .php:2) in D:\www\blog\wp-content\themes\atahualpa\functions\bfa_get_options .php on line 512

sorry, there looks like there was a change in templates from 3.5.3 to 3.6.0 and I (oops) didn't test it in 3.6.0

replace the first part of the code:
[html]<?php
/*
Template Name: pregtest template
*/
?>
<?php // Do not delete these lines ?>
------
<?php /* get all options: */
include (TEMPLATEPATH . '/functions/bfa_get_options.php');
get_header();

#global $bfa_ata;
// You can start editing below:
?>

with

Here is the text :

à la une . Dès que jaurais le temps. Étienne

In the file , you will find what i get.

And there is no difference.

can anyone verify this ?