[imp] Language stuck to english and making me nuts

[Sebastien Courtaud]

Hi,
 
            I'm new to IMP but not to PHP (I thought so until today). I
have a running installation of imp. Everything works ok except the
language settings.
 
I have tried all the solutions I could find on the web but I get
desperate. Could anyone explain me why my IMP 3.2.1 refuses to switch
form english to french as a default language. 
Its even worse because in the screenshots on horde.org, the orange theme
is in french.
 
Help please...
 
 
Sebastien