Currently running 2.5.0_beta1 with server 1.7.3; up-to-date 10.6.2. I noted this time that X11 was *not* shown as "(not responding)" in the Force Quit list. I'm not sure if I saw that before. Other symptoms the same as before: X11 menus can be pulled down but it's otherwise totally nonresponsive to keyboard and mouse events. Attached are Activity Monitor samples of X11 and quartz-wm, as Jeremy suggested grabbing last time. It's possibly relevant that at the time it froze, I had just quit out of iTunes. Also, a Time Machine backup started at more or less the same time. regards, tom lane Sampling process 5667 for 3 seconds with 1 millisecond of run time between samples Sampling completed, processing symbols... Analysis of sampling X11.bin (pid 5667) every 1 millisecond Call graph: 2382 Thread_256279 DispatchQueue_1: com.apple.main-thread (serial) 2382 start 2382 main 2382 mach_msg_server 2382 mach_startup_server 2382 _Xstart_x11_server 2382 do_start_x11_server 2382 server_main 2382 X11ApplicationMain 2382 -[NSApplication run] 2382 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] 2382 _DPSNextEvent 2382 BlockUntilNextEventMatchingListInMode 2382 ReceiveNextEventCommon 2382 RunCurrentEventLoopInMode 2382 CFRunLoopRunSpecific 2382 __CFRunLoopRun 2382 mach_msg 2382 mach_msg_trap 2382 Thread_256364 DispatchQueue_2: com.apple.libdispatch-manager (serial) 2382 start_wqthread 2382 _pthread_wqthread 2382 _dispatch_worker_thread2 2382 _dispatch_queue_invoke 2382 _dispatch_mgr_invoke 2382 kevent 2382 Thread_256367 2382 thread_start 2382 _pthread_start 2382 server_thread 2382 dix_main 2382 Dispatch 2382 WaitForSomething 2382 select$DARWIN_EXTSN 2382 Thread_256368 2382 thread_start 2382 _pthread_start 2382 xpbproxy_x_thread 2382 xpbproxy_input_loop 2382 _pthread_cond_wait 2382 __semwait_signal 2382 Thread_256381 2382 thread_start 2382 _pthread_start 2382 DarwinProcessFDAdditionQueue_thread 2382 _pthread_cond_wait 2382 __semwait_signal 2382 Thread_256387 2382 thread_start 2382 _pthread_start 2382 __CFSocketManager 2382 select$DARWIN_EXTSN 2382 Thread_256391 2382 thread_start 2382 _pthread_start 2382 _xp_async_thread 2382 _xp_async_dequeue 2382 _pthread_cond_wait 2382 __semwait_signal 2382 Thread_342775 2382 thread_start 2382 _pthread_start 2382 __NSThread__main__ 2382 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] 2382 CFRunLoopRunSpecific 2382 __CFRunLoopRun 2382 mach_msg 2382 mach_msg_trap 2382 Thread_342784: JavaScriptCore: FastMalloc scavenger 2382 thread_start 2382 _pthread_start 2382 WTF::TCMalloc_PageHeap::runScavengerThread(void*) 2382 WTF::TCMalloc_PageHeap::scavengerThread() 2382 _pthread_cond_wait 2382 __semwait_signal 2382 Thread_746520 2382 start_wqthread 2382 _pthread_wqthread 2382 __workq_kernreturn Total number in stack (recursive counted multiple, when >=5): 7 _pthread_start 7 thread_start Sort by top of stack, same collapsed (when >= 5): __semwait_signal 9528 mach_msg_trap 4764 select$DARWIN_EXTSN 4764 __workq_kernreturn 2382 kevent 2382 Sample analysis of process 5667 written to file /dev/stdout Sampling process 5729 for 3 seconds with 1 millisecond of run time between samples Sampling completed, processing symbols... Analysis of sampling quartz-wm (pid 5729) every 1 millisecond Call graph: 2499 Thread_256382 DispatchQueue_1: com.apple.main-thread (serial) 2499 start 2499 main 2499 CFRunLoopRun 2499 CFRunLoopRunSpecific 2499 __CFRunLoopRun 2499 mach_msg 2499 mach_msg_trap 2499 Thread_256385 DispatchQueue_2: com.apple.libdispatch-manager (serial) 2499 start_wqthread 2499 _pthread_wqthread 2499 _dispatch_worker_thread2 2499 _dispatch_queue_invoke 2499 _dispatch_mgr_invoke 2499 kevent 2499 Thread_256386 2499 thread_start 2499 _pthread_start 2499 __CFSocketManager 2499 select$DARWIN_EXTSN Total number in stack (recursive counted multiple, when >=5): Sort by top of stack, same collapsed (when >= 5): kevent 2499 mach_msg_trap 2499 select$DARWIN_EXTSN 2499 Sample analysis of process 5729 written to file /dev/stdout