Index: models.py
===================================================================
--- models.py	(revision 3439)
+++ models.py	(working copy)
@@ -243,8 +243,9 @@
                 raise SiteProfileNotAvailable
             try:
                 app_label, model_name = settings.AUTH_PROFILE_MODULE.split('.')
+                models.get_models() # burn in cache
                 model = models.get_model(app_label, model_name)
-                self._profile_cache = model._default_manager.get(user__id__exact=self.id)
+                self._profile_cache = model._default_manager.get(pk=self.id)
             except (ImportError, ImproperlyConfigured):
                 raise SiteProfileNotAvailable
         return self._profile_cache