--- loncom/homework/lonhomework.pm	2007/11/03 00:52:06	1.282
+++ loncom/homework/lonhomework.pm	2007/11/13 23:26:08	1.284
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # The LON-CAPA Homework handler
 #
-# $Id: lonhomework.pm,v 1.282 2007/11/03 00:52:06 albertel Exp $
+# $Id: lonhomework.pm,v 1.284 2007/11/13 23:26:08 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -543,7 +543,8 @@ sub due_date {
 	&Apache::lonxml::debug("looking for first_access $first_access");
 	if (defined($first_access)) {
 	    $interval = $first_access+$interval;
-	    $date = ($interval < $due_date)? $interval : $due_date;
+	    $date = (!$due_date || $interval < $due_date) ? $interval
+                                                          : $due_date;
 	} else {
 	    $date = $due_date;
 	}
@@ -683,9 +684,9 @@ sub handle_save_or_undo {
     my $error=0;
     if ($env{'form.Undo'} eq &mt('undo')) {
 	my $error=0;
-	if (!copy($file,$filetmp)) { $error=1; }
-	if ((!$error) && (!copy($filebak,$file))) { $error=1; }
-	if ((!$error) && (!move($filetmp,$filebak))) { $error=1; }
+	if (!&File::Copy::copy($file,$filetmp)) { $error=1; }
+	if ((!$error) && (!&File::Copy::copy($filebak,$file))) { $error=1; }
+	if ((!$error) && (!&File::Copy::move($filetmp,$filebak))) { $error=1; }
 	if (!$error) {
 	    &Apache::lonxml::info("<p><b>".
 				  &mt("Undid changes, Switched [_1] and [_2]",