added a check to verify strrpos actually returned something useful before trying to call substr

fedora_repository.module

@@ -522,10 +522,13 @@ function fedora_repository_replace_stream_form_submit($form, &$form_state) {
   $file = $form_state['values']['file'];
   $pid = $form_state['values']['pid'];
   $dsid = $form_state['values']['dsId'];
-
+  $dsLabel = $form_state['values']['dsLabel'];
   // Remove the original file extension from the label and add the new one
-  $dsLabel = substr($form_state['values']['dsLabel'], 0, strrpos($form_state['values']['dsLabel'], '.'));
+  $indexOfDot = strrpos($dsLabel,'.');//use strrpos to get the last dot
+  if($indexOfDot !== FALSE){
+  $dsLabel = substr($dsLabel, 0, $indexOfDot);
   $dsLabel .= substr($file->filename, strrpos($file->filename, '.')); // Add the file extention to the end of the label.;
+  }
   module_load_include('inc', 'Fedora_Repository', 'MimeClass');
   module_load_include('inc', 'Fedora_Repository', 'ObjectHelper');
   module_load_include('inc', 'Fedora_Repository', 'ConnectionHelper');