Index: fb.module
===================================================================
--- fb.module	(revision 4868)
+++ fb.module	(working copy)
@@ -1017,10 +1017,10 @@
     // $object->init may be present when object is a user.
     $fbu = substr($object->init, 0, $pos);
   }
-  elseif ($pos = strpos($object->name, '@facebook')) {
+  elseif (!empty($object->name) && ($pos = strpos($object->name, '@facebook'))) {
     $fbu = substr($object->name, 0, $pos);
   }
-  elseif ($object->uid > 0) {
+  elseif (!empty($object->uid)) {
     // This can be expensive on pages with many comments or nodes!
     $fbu = fb_get_fbu($object->uid);
   }