Openerp settup problem

Hi,

I chose the option database to set the Turkish language. After adjustment of the database, user input is the main page when I got the error is as follows. The other problem is I can not access the Firefox web browser to the server, is a blank page.

OpenERP WebClient Error
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Client Traceback (most recent call last):
  File "C:\Program Files\OpenERP 6.1rc1-20120112-173907\server\openerp\addons\web\common\http.py", line 176, in dispatch
  File "C:\Program Files\OpenERP 6.1rc1-20120112-173907\server\openerp\addons\web\controllers\main.py", line 243, in translations
  File "babel\messages\catalog.pyo", line 522, in __iter__
  File "babel\messages\catalog.pyo", line 302, in _get_mime_headers
  File "babel\dates.pyo", line 501, in format_datetime
  File "babel\core.pyo", line 212, in parse
  File "babel\core.pyo", line 137, in __init__
UnknownLocaleError: unknown locale 'en'