Simple Extension to Django's default ModelBackend to force it to select a profile in addition to the user.

settings.py

AUTHENTICATION_BACKENDS = ('project_name.wherever.you.put.it.SmartModelBackend',)

smartmodelbackend.py

from django.contrib.auth.backends import ModelBackend
from django.contrib.auth.models import User

class SmartModelBackend(ModelBackend):
    def get_user(self, user_id):
        try:
            #note that 'profile' needs to be set to whatever your profile's related_name is.
            return User.objects.select_related('profile').get(pk=user_id)
        except User.DoesNotExist:
            return None