I have exactly the same problem related to spanish language. I installed a new wp 2.7 and it is ok in english, but if I put the spanish .mo and add the corresponding define line in wp-config.php: define (‘WPLANG’, ‘es_ES’); then I can see the site, front end, but if I try to log in I get a 500 internal server error.
To access the admin I need to define back to english, otherwise I cannot enter the admin panel. I have tried different spanish .mo from official wordpres, argentine, etc … I have not found the solution. I thing it is the .mo file.
Any sugestions?
Gracias
