This message occures when try to loginto database

"Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application."

Tried to restore the database from backup, but same failure.

If I try to login from /database/selector i get this message:

"Forbidden
You don't have the permission to access the requested resource. It is either read-protected or not readable by the server."

this is what I got from the log:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_cron.py", line 129, in _callback    getattr(model, method_name)(cr, uid, *args)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper    return old_api(self, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/addons/fetchmail/fetchmail.py", line 166, in _fetch_mails    return self.fetch_mail(cr, uid, ids, context=context)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper    return old_api(self, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/addons/fetchmail/fetchmail.py", line 242, in fetch_mail    server.write({'date': time.strftime(tools.DEFAULT_SERVER_DATETIME_FORMAT)})  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 248, in wrapper    return new_api(self, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 574, in new_api    result = method(self._model, cr, uid, self.ids, *args, **old_kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/addons/fetchmail/fetchmail.py", line 265, in write    res = super(fetchmail_server, self).write(cr, uid, ids, values, context=context)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper    return old_api(self, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 381, in old_api    result = method(recs, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3842, in write    self._write(old_vals)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 248, in wrapper    return new_api(self, *args, **kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 574, in new_api    result = method(self._model, cr, uid, self.ids, *args, **old_kwargs)  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3962, in _write    raise MissingError(_('One of the records you are trying to modify has already been deleted (Document type: %s).') % self._description)MissingError: (u'One of the records you are trying to modify has already been deleted (Document type: POP/IMAP Server).', None)