Index: modules/file/file.field.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/file/file.field.inc,v
retrieving revision 1.10
diff -u -p -r1.10 file.field.inc
--- modules/file/file.field.inc	11 Nov 2009 08:32:35 -0000	1.10
+++ modules/file/file.field.inc	29 Nov 2009 19:06:05 -0000
@@ -256,7 +256,21 @@ function file_field_update($obj_type, $o
   // Check for files that have been removed from the object.
 
   // On new revisions, old files are always maintained in the previous revision.
-  if ($object->is_new || (isset($object->revision) && $object->revision)) {
+  if (isset($object->revision) && $object->revision) {
+    return;
+  }
+
+  // Make sure to set the status of the file to permanent so it is not garbage
+  // collected as a temporary file.
+  foreach ($items as $delta => $item) {
+    $file = file_load($item['fid']);
+    $file->status = $item['status'] = 1;
+    file_save($file);
+  }
+
+  // If the object is new, we're done, we don't need to clean up any
+  // existing file fields.
+  if ($object->is_new) {
     return;
   }