This is an odd one. I had Monitor running yesterday on my mid-2010 MacBook Pro running OS X 10.6.4. I quit Monitor and fired it up today, and it fails to start. I see this in the Console.app window :
03/11/2010 06:53:04 org.x.startx[31987] font_cache: Scanning user font directories to generate X11 font caches
03/11/2010 06:53:04 org.x.startx[31987] font_cache: Updating FC cache
03/11/2010 06:53:04 org.x.privileged_startx[32000] font_cache: Scanning system font directories to generate X11 font caches
03/11/2010 06:53:04 defaults[32020]
The domain/default pair of (org.x.X11, dpi) does not exist
03/11/2010 06:53:05 org.x.startx[31987] xauth: creating new authority file /Users/phil/.serverauth.31987
03/11/2010 06:53:05 org.x.startx[31987] Xquartz: Unable to locate waiting server: org.x.X11
03/11/2010 06:53:05 org.x.startx[31987] Xquartz: X11.app = /Applications/Utilities/X11.app/Contents/MacOS/X11
03/11/2010 06:53:05 org.x.startx[31987] Xquartz: Starting X server: /Applications/Utilities/X11.app/Contents/MacOS/X11 --listenonly
03/11/2010 06:53:05 org.x.startx[31987] X11.app: main(): argc=2
03/11/2010 06:53:05 org.x.startx[31987] argv[0] = /Applications/Utilities/X11.app/Contents/MacOS/X11.bin
03/11/2010 06:53:05 org.x.startx[31987] argv[1] = --listenonly
03/11/2010 06:53:05 org.x.startx[31987] Waiting for startup parameters via Mach IPC.
03/11/2010 06:53:05 org.x.startx[31987] X11.app: Listening on socket for fd handoff: (4) /var/tmp/tmp.0.NX6Aar
03/11/2010 06:53:05 org.x.startx[31987] X11.app: Thread created for handoff. Returning success to tell caller to connect and push the fd.
03/11/2010 06:53:05 org.x.startx[31987] Xquartz: Handoff connection established (try 1 of 5) on fd 7, “/var/tmp/tmp.0.NX6Aar”. Sending message.
03/11/2010 06:53:05 org.x.startx[31987] Xquartz: Message sent. Closing handoff fd.
03/11/2010 06:53:05 org.x.startx[31987] X11.app: do_start_x11_server(): argc=6
03/11/2010 06:53:05 org.x.startx[31987] argv[0] = /usr/X11/bin/X
03/11/2010 06:53:05 org.x.startx[31987] argv[1] = :0
03/11/2010 06:53:05 org.x.startx[31987] argv[2] = -nolisten
03/11/2010 06:53:05 org.x.startx[31987] argv[3] = tcp
03/11/2010 06:53:05 org.x.startx[31987] argv[4] = -auth
03/11/2010 06:53:05 org.x.startx[31987] argv[5] = /Users/phil/.serverauth.31987
03/11/2010 06:53:05 org.x.startx[31987] X11.app: Received new $DISPLAY fd: 8 … sleeping to allow xinitrc to catchup.
03/11/2010 06:53:06 org.x.startx[31987] Xquartz starting:
03/11/2010 06:53:06 org.x.startx[31987] X.Org X Server 1.4.2-apple53
03/11/2010 06:53:06 org.x.startx[31987] Build Date: 20100211
03/11/2010 06:53:06 org.x.privileged_startx[32000] font_cache: Updating FC cache
03/11/2010 06:53:07 org.x.startx[31987] (EE) XKB: Couldn’t open rules file /usr/X11/share/X11/xkb/rules/base
03/11/2010 06:53:07 org.x.startx[31987] (EE) XKB: Couldn’t open rules file /usr/X11/share/X11/xkb/rules/base
03/11/2010 06:53:07 org.x.startx[31987] font_cache: Done
03/11/2010 06:53:08 org.x.startx[31987] X11.app Handing off fd to server thread via DarwinListenOnOpenFD(8)
03/11/2010 06:53:08 org.x.startx[31987] DarwinListenOnOpenFD: 8
03/11/2010 06:53:08 org.x.startx[31987] Calling ListenOnOpenFD() for new fd: 8
03/11/2010 06:53:09 org.x.privileged_startx[32000] font_cache: Done
03/11/2010 06:53:10 Firewall[76] mono is listening from 127.0.0.1:52842 proto=6
03/11/2010 06:53:10 [0x0-0x11b31b2].net.deadline.DeadlineMonitor[31960] Gtk not found (missing LD_LIBRARY_PATH to libgtk-x11-2.0.so.0?), using built-in colorscheme
03/11/2010 06:53:10 [0x0-0x11b31b2].net.deadline.DeadlineMonitor[31960] System.Net.Sockets.SocketOptionName 0x1b is not supported at IPv6 level
The Monitor icon vanishes. I’ve no idea why. To the best of my knowledge, nothing has changed on this system since yesterday.