diff --git a/pandora_server/ChangeLog b/pandora_server/ChangeLog
index db09b6f99a..8864296d58 100644
--- a/pandora_server/ChangeLog
+++ b/pandora_server/ChangeLog
@@ -1,3 +1,15 @@
+2011-06-23  Koichiro Kikuchi  <koichiro@rworks.jp>
+
+	* lib/PandoraFMS/Tools.pm: Checked if pandora_server is already
+	  running, in order to prevent multiple instances with same PID
+	  file from running. And made PID file permissions 644, rather
+	  than 666. 
+
+	* bin/pandora_server: Remove PID file on shutdown.
+
+	* FreeBSD/pandora_server: Use -P option for PID file instead of
+	  pgrep.
+
 2011-06-22  Ramon Novoa  <rnovoa@artica.es>
 
 	* lib/PandoraFMS/Config.pm: Added a new SNMP server (enterprise).
diff --git a/pandora_server/FreeBSD/pandora_server b/pandora_server/FreeBSD/pandora_server
index 4d9164f037..f8ddeafcc3 100755
--- a/pandora_server/FreeBSD/pandora_server
+++ b/pandora_server/FreeBSD/pandora_server
@@ -26,25 +26,11 @@ load_rc_config $name
 
 PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin
 
-command=/usr/local/bin/${name}
-command_args="-D /usr/local/etc/pandora/pandora_server.conf"
-
 pidfile=/var/run/$name.pid
+command=/usr/local/bin/${name}
+command_args="-D -P ${pidfile} /usr/local/etc/pandora/pandora_server.conf"
 required_files="/usr/local/etc/pandora/pandora_server.conf"
-start_postcmd=start_postcmd
-stop_postcmd=stop_postcmd
 
 procname="/usr/local/bin/perl"
 
-start_postcmd()
-{
-	PANDORA_PID=`pgrep -f -j none $name`
-	echo $PANDORA_PID > $pidfile
-}
-
-stop_postcmd()
-{
-	rm -f $pidfile
-}
-
 run_rc_command "$1"
diff --git a/pandora_server/bin/pandora_server b/pandora_server/bin/pandora_server
index 482e8464c2..a2eaecbdf8 100755
--- a/pandora_server/bin/pandora_server
+++ b/pandora_server/bin/pandora_server
@@ -56,6 +56,9 @@ sub pandora_shutdown () {
 
 	print_message (\%Config, ' [*] Shutting down ' . $Config{'servername'} . "(received signal)...\n", 1);
 	db_disconnect ($DBH);
+	if ($Config{'PID'} ne "") {
+		unlink($Config{'PID'}) or logger (\%Config, "[W] Could not remove PID file: $!",1);
+	}
 	exit (0);
 }
 
diff --git a/pandora_server/lib/PandoraFMS/Tools.pm b/pandora_server/lib/PandoraFMS/Tools.pm
index 86dcf8f8d9..2d9d8be444 100644
--- a/pandora_server/lib/PandoraFMS/Tools.pm
+++ b/pandora_server/lib/PandoraFMS/Tools.pm
@@ -284,14 +284,26 @@ sub pandora_daemonize {
 	defined(my $pid = fork)     or die "Can't fork: $!";
 	exit if $pid;
 	setsid                      or die "Can't start a new session: $!";
-	umask 0;
 
 	# Store PID of this process in file presented by config token
 	if ($pa_config->{'PID'} ne ""){
+
+		if ( -e $pa_config->{'PID'} && open (FILE, $pa_config->{'PID'})) {
+			$pid = <FILE> + 0;
+			close FILE;
+
+			# check if pandora_server is running
+			if (kill (0, $pid)) {
+				die "[FATAL] pandora_server already running, pid: $pid.";
+			}
+			logger ($pa_config, '[W] Stale PID file, overwriting.', 1);
+		}
+		umask 022;
 		open (FILE, "> ".$pa_config->{'PID'}) or die "[FATAL] Cannot open PIDfile at ".$pa_config->{'PID'};
 		print FILE "$$";
 		close (FILE);
 	}
+	umask 0;
 }