Index: typo3/sysext/beuser/mod/index.php
===================================================================
--- typo3/sysext/beuser/mod/index.php	(revision 3859)
+++ typo3/sysext/beuser/mod/index.php	(working copy)
@@ -1566,7 +1566,8 @@
 			// Process and visualized each active session as a table row:
 		if (is_array($sessions)) {
 			foreach ($sessions as $session) {
-				$hostName = ($session['ses_iplock'] != '[DISABLED]' ? gethostbyaddr($session['ses_iplock']) : '[DISABLED]');
+				$hostByAddr = @gethostbyaddr($session['ses_iplock']) ? gethostbyaddr($session['ses_iplock']) : '';
+				$hostName = ($session['ses_iplock'] != '[DISABLED]' ? $hostByAddr : '[DISABLED]');
 				$outTable .= '
 					<tr class="bgColor4" height="17" valign="top">' .
 						'<td nowrap="nowrap">' .