Ben, I gave you executable a try (it crashed by the way when I tried the second account): Here is what appears in the Console Messages: ***This is where I started up X11 in the first account (which is an admin user) by starting something from Terminal (in this case it was nedit, but oclock works as well). 12/21/07 7:00:02 AM org.x.X11[723] checking display 0 12/21/07 7:00:02 AM org.x.X11[723] display_exists_p(0) 12/21/07 7:00:02 AM org.x.X11[723] server_name = 12612 12/21/07 7:00:02 AM org.x.X11[723] TransformProcessType: Success 12/21/07 7:00:02 AM org.x.X11[723] TransformProcessType: Success 12/21/07 7:00:02 AM org.x.X11[723] Launchd command line argument noticed. 12/21/07 7:00:02 AM org.x.X11[723] X11.app starting: 12/21/07 7:00:02 AM org.x.X11[723] X.org Release 7.2 12/21/07 7:00:02 AM org.x.X11[723] X.Org Xquartz X Server 1.3.0-apple5 12/21/07 7:00:02 AM org.x.X11[723] Build Date: 20071210 12/21/07 7:00:02 AM org.x.X11[723] Xquartz: run by launchd for fd 0 12/21/07 7:00:02 AM org.x.X11[723] _XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created. ***This is where I fast-user switched to the second account (which is a normal user) 12/21/07 7:00:32 AM com.apple.launchd[1] (com.apple.UserEventAgent- LoginWindow[734]) Exited: Terminated ***Attempt to start oclock from Terminal.app from the second account 12/21/07 7:00:45 AM org.x.X11[723] AUDIT: Fri Dec 21 07:00:45 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:00:45 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:00:56 AM org.x.X11[723] AUDIT: Fri Dec 21 07:00:56 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:00:56 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:06 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:06 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:06 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:16 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:16 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:16 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:26 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:26 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:26 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:36 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:36 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:36 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:46 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:46 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:46 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:01:57 AM org.x.X11[723] AUDIT: Fri Dec 21 07:01:57 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:01:57 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:02:07 AM org.x.X11[723] AUDIT: Fri Dec 21 07:02:07 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:02:07 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:02:17 AM org.x.X11[723] AUDIT: Fri Dec 21 07:02:17 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:02:17 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:02:27 AM org.x.X11[723] AUDIT: Fri Dec 21 07:02:27 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:02:27 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:02:37 AM org.x.X11[723] AUDIT: Fri Dec 21 07:02:37 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:02:37 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 12/21/07 7:02:47 AM org.x.X11[723] AUDIT: Fri Dec 21 07:02:47 2007: 724 X11: client 5 rejected from local host (uid 503) 12/21/07 7:02:47 AM org.x.X11[723] Auth name: MIT-MAGIC-COOKIE-1 ID: -1 ***This is where I logged out of the second account to stop the launchd infinite loop of trying to continuously start X11 and fail. 12/21/07 7:03:02 AM com.apple.launchd[1] (com.apple.UserEventAgent- LoginWindow[819]) Exited: Terminated Here is the crash report dump from the attempt to start X11 (by launching oclock from Terminal): Process: X11 [778] Path: /Applications/Utilities/X11.app/Contents/MacOS/X11 Identifier: X11 Version: ??? (???) Code Type: X86 (Native) Parent Process: launchd [743] Date/Time: 2007-12-21 07:00:45.867 -0500 OS Version: Mac OS X 10.5.1 (9B18) Report Version: 6 Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000000000000 Crashed Thread: 0 Thread 0 Crashed: 0 libSystem.B.dylib 0x938aa590 strlen + 16 1 libSystem.B.dylib 0x938a2ab6 __vfprintf + 290 2 libSystem.B.dylib 0x938d7603 vfprintf_l + 100 3 libSystem.B.dylib 0x938d7597 fprintf + 75 4 org.x.X11 0x0000247f 0x1000 + 5247 5 org.x.X11 0x000018da 0x1000 + 2266 Thread 0 crashed with X86 Thread State (32-bit): eax: 0xffffffff ebx: 0x938a299f ecx: 0x00000001 edx: 0x00000000 edi: 0x00000001 esi: 0x00000001 ebp: 0xbfffef78 esp: 0xbfffe81c ss: 0x0000001f efl: 0x00010286 eip: 0x938aa590 cs: 0x00000017 ds: 0x0000001f es: 0x0000001f fs: 0x00000000 gs: 0x00000037 cr2: 0x00000000 Binary Images: 0x1000 - 0x2fff +org.x.X11 2.1.1 (???) <62d310dc84d80698fdc1f8dea0ad53c4> /Applications/Utilities/X11.app/ Contents/MacOS/X11 0x6000 - 0x6ff1 +libXau.6.dylib ??? (???) <af0fefbbf38efd4df94bedea64d5019d> /usr/X11/lib/libXau.6.dylib 0x1a000 - 0x27fff +libxcb.1.dylib ??? (???) <15cdb4dae02369daf3b0373f3fee97d9> /usr/X11/lib/libxcb.1.dylib 0x34000 - 0x36fef +libXdmcp.6.dylib ??? (???) <a12913daa7d2b4efb341cb698f4182fa> /usr/X11/lib/libXdmcp.6.dylib 0x13a000 - 0x225fff +libX11.6.dylib ??? (???) <d5c89933ecfd158e6ee09726b0610c5b> /usr/X11/lib/libX11.6.dylib 0x8fe00000 - 0x8fe2d883 dyld 95.3 (???) <81592e798780564b5d46b988f7ee1a6a> /usr/lib/dyld 0x90260000 - 0x9033ffff libobjc.A.dylib ??? (???) <5eda47fec2d0e7853b3506aa1fd2dafa> /usr/lib/libobjc.A.dylib 0x9096e000 - 0x90975fe9 libgcc_s.1.dylib ??? (???) <f53c808e87d1184c0f9df63aef53ce0b> /usr/lib/libgcc_s.1.dylib 0x9186a000 - 0x918a0fff com.apple.SystemConfiguration 1.9.0 (1.9.0) <7919d9588c3b0d556646e555b7193f1f> /System/Library/Frameworks/ SystemConfiguration.framework/Versions/A/SystemConfiguration 0x91b09000 - 0x91b66ffb libstdc++.6.dylib ??? (???) <04b812dcec670daa8b7d2852ab14be60> /usr/lib/libstdc++.6.dylib 0x923da000 - 0x92404fef libauto.dylib ??? (???) <d468bc4a8a69343f1748c293db1b57fb> /usr/lib/libauto.dylib 0x9364b000 - 0x93783ff7 libicucore.A.dylib ??? (???) <afcea652ff2ec36885b2c81c57d06d4c> /usr/lib/libicucore.A.dylib 0x938a1000 - 0x939fbfe3 libSystem.B.dylib ??? (???) <8ecc83dc0399be3946f7a46e88cf4bbb> /usr/lib/libSystem.B.dylib 0x93f99000 - 0x93f9afef libmathCommon.A.dylib ??? (???) /usr/lib/ system/libmathCommon.A.dylib 0x9636a000 - 0x9649cfe7 com.apple.CoreFoundation 6.5 (476) <8bfebc0dbad6fc33bea0fa00a1b9ec37> /System/Library/Frameworks/ CoreFoundation.framework/Versions/A/CoreFoundation 0xfffe8000 - 0xfffebfff libobjc.A.dylib ??? (???) /usr/lib/ libobjc.A.dylib 0xffff0000 - 0xffff1780 libSystem.B.dylib ??? (???) /usr/lib/ libSystem.B.dylib Merle