Inconsistent behavior for editing table records

phpMyAdmin version : 3.2.0.1, on FC9 with Apache 2.2.9 and PHP 5.2.9.
MySQL version 5.0.77 (both client and server), running locally (host=localhost).
Browser Firefox 3.0.11.

I created a database with a single table :

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
CREATE DATABASE `HA_adherents` /*!40100 DEFAULT CHARACTER SET utf8 */
CREATE TABLE `adherents` (
`ID` int(11) NOT NULL,
`Nom` varchar(40) NOT NULL,
`Prénom` varchar(40) NOT NULL,
`Adresse` varchar(100) NOT NULL,
`CP` int(11) NOT NULL,
`Ville` varchar(30) NOT NULL,
`Tél` text,
`E-mail` varchar(40) NOT NULL,
`CallSign` varchar(8) NOT NULL,
`Mdp` varchar(10) NOT NULL,
`Valide` tinyint(1) default NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

I can import records in the above table, but then when I want to edit any row, I get the following error message as soon as I click on the "pencil" icon :
"Method Not Implemented
GET to /phpMyAdmin/tbl_change.php not supported."

The same error also happens on other databases/tables on the same server. More surprisingly, sometimes it happens only on some tables of a database, but never happens on other tables of the same database; in other words, editing row contents works perfectly fine on some tables, but always yields the above error on other tables within the same database.
This error happens whichever "MySQL user" is used by PMA (ie. even for "root" user).