Index: boxes.module
===================================================================
--- boxes.module	(revision 14)
+++ boxes.module	(working copy)
@@ -152,7 +152,12 @@
 function boxes_footer() {
   // Besure the page isn't a 404 or 403.
   $headers = drupal_set_header();
-  foreach (explode("\n", $headers) as $header) {
+
+  // Support for Pressflow patched drupal_set_header
+  if (!is_array($headers)) {
+    $headers = explode("\n", $headers);
+  }
+
+  foreach ($headers as $header) {
     if ($header == "HTTP/1.1 404 Not Found" || $header == "HTTP/1.1 403 Forbidden") {
       return;
     }