Umlauts in Project-Description do not work

following on the screen(An unexpected exception appeared. Please contact your system administrator.)
Console:
2012-07-31 09:36:09,996 - ERROR - tvb.interface.web.controllers.basecontroller - 'ascii' codec can't encode character u'\xe4' in position 13: ordinal not in ran
ge(128)
Traceback (most recent call last):
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\interfaces\web\controllers\basecontroller.py", line 95, in deco
template_dict = func(*a, **b)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\interfaces\web\controllers\basecontroller.py", line 78, in deco
return func(*a, **b)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\interfaces\web\controllers\userscontroller.py", line 35, in deco
return func(*a, **b)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\interfaces\web\controllers\projectcontroller.py", line 181, in editone
self._persist_project(data, project_id, is_create, current_user)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\interfaces\web\controllers\projectcontroller.py", line 139, in _persist_project
saved_project = self.project_service.store_project(current_user, is_create, project_id, **data)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\core\services\projectservice.py", line 95, in store_project
self.structure_helper.write_project_metadata(current_proj)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\core\entities\file\fileshelper.py", line 135, in write_project_metadata
XMLWriter(meta_entity).write(proj_path)
File "C:\Users\jmersmann.CODEBOX\Desktop\TVB_Distribution\library.zip\tvb\core\entities\file\metadatahandler.py", line 143, in write
node.appendChild(doc.createTextNode(str(att_value)))
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe4' in position 13: ordinal not in range(128)