What is your LANG environment variable set to ? This might be the problem.
You can override the LANG environment setting by editing the ressource
file $HOME/.thotrc and set up LANG=en int the corresponding application
block, or in the [thot_lib] one.
Otherwise, check that Thot/config/en-thotdialogue, Thot/config/en-libdialogue
and Thot/config/en-thotmessage exists. (The same with fr- prefix should also
be available).
hope this help,
Daniel