Index: base.py
===================================================================
--- base.py	(revision 7511)
+++ base.py	(working copy)
@@ -433,7 +433,7 @@
 
     def _get_FIELD_filename(self, field):
         if getattr(self, field.attname): # value is not blank
-            return os.path.join(settings.MEDIA_ROOT, getattr(self, field.attname))
+            return os.path.normpath(os.path.join(settings.MEDIA_ROOT, getattr(self, field.attname)))
         return ''
 
     def _get_FIELD_url(self, field):