On my friends Macbook with latest V3.0 build (he has never installed MacFUSE), there are occasional cases where Parallels CPU goes up, windowserver CPU also increases -- in these cases the mouse goes crazy, jumping all over the place. Today there was a warning dialog stating that MacFUSE could not connect, and he managed to get this sample while Parallels was not responding: Analysis of sampling pid 666 every 10.000000 milliseconds Call graph: 296 Thread_0f07 296 0x66b9 296 0x6792 296 0x41dc9 296 0x388d5d 296 0x5ab264 296 0x5ab14b 296 0x5fec31 296 0x40755a 296 SendEventToEventTarget 296 SendEventToEventTargetInternal(OpaqueEventRef*, OpaqueEventTargetRef*, HandlerCallRec*) 296 DispatchEventToHandlers(EventTargetRec*, OpaqueEventRef*, HandlerCallRec*) 296 ToolboxEventDispatcherHandler(OpaqueEventHandlerCallRef*, OpaqueEventRef*, void*) 296 SendEventToEventTarget 296 SendEventToEventTargetInternal(OpaqueEventRef*, OpaqueEventTargetRef*, HandlerCallRec*) 296 DispatchEventToHandlers(EventTargetRec*, OpaqueEventRef*, HandlerCallRec*) 296 0x40eb4e 296 0x375ca1 296 0x370915 296 0x382684 296 0x386536 296 0x3aa1c1 296 0x3856dd 296 0x3854ef 296 0x583ebb 296 0x3796d7 296 0x3542d3 296 0x12d5f3 296 0x32a58d 296 0x32a51e 296 0x550a56 296 0x54d735 296 0x54d6bd 296 unmount 296 unmount 296 Thread_1003 296 _pthread_body 296 CAPThread::Entry(CAPThread*) 296 HALRunLoop::OwnThread(void*) 296 CFRunLoopRunInMode 296 CFRunLoopRunSpecific 296 mach_msg_trap 296 mach_msg_trap 296 Thread_1103 296 _pthread_body 296 0x3b6836 296 0x45508c 253 0x45465d 253 semaphore_timedwait_signal_trap 253 semaphore_timedwait_signal_trap 43 ioctl 43 ioctl 296 Thread_1203 296 _pthread_body 296 0x3b6836 296 0x43b9e2 296 0x64bb3c 295 0x648c0a 295 usleep 295 mach_wait_until 295 mach_wait_until 1 0x648c20 1 0x648c20 296 Thread_1303 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1403 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1503 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1603 296 _pthread_body 296 0x65f6cc 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1703 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1803 296 _pthread_body 296 0x725401 296 QList<TGDev>::append(TGDev const&) 296 0x659eb4 296 0x7251cc 296 semaphore_timedwait_trap 296 semaphore_timedwait_trap 296 Thread_1903 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1a03 296 _pthread_body 296 0x725401 296 QList<TGDev>::append(TGDev const&) 296 0x659eb4 296 0x7251cc 296 semaphore_timedwait_trap 296 semaphore_timedwait_trap 296 Thread_1b03 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1c03 296 _pthread_body 296 0x725401 296 QList<TGDev>::append(TGDev const&) 296 0x659eb4 296 0x7251cc 296 semaphore_timedwait_trap 296 semaphore_timedwait_trap 296 Thread_1d03 296 _pthread_body 296 0x3b6836 296 0x64be68 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap 296 Thread_1e03 296 _pthread_body 296 0x3b6836 296 0x43ac32 296 CFRunLoopRun 296 CFRunLoopRunSpecific 296 mach_msg_trap 296 mach_msg_trap 296 Thread_1f03 296 _pthread_body 296 0x3b6836 296 0x43b905 296 usleep 295 mach_wait_until 295 mach_wait_until 1 nanosleep 1 nanosleep 296 Thread_2003 296 _pthread_body 296 0x45a2e1 296 0x54dd0b 296 0x54d22c 296 0x6b2fa6 296 0x52e8ea 296 semaphore_wait_signal_trap 296 semaphore_wait_signal_trap Total number in stack (recursive counted multiple, when >=5): 17 _pthread_body 11 0x3b6836 9 semaphore_wait_signal_trap 7 0x64be68 Sort by top of stack, same collapsed (when >= 5): semaphore_wait_signal_trap 2664 semaphore_timedwait_trap 888 mach_msg_trap 592 mach_wait_until 590 unmount 296 semaphore_timedwait_signal_trap 253 ioctl 43 Sample analysis of process 666 written to file /dev/stdout Sampling process 666 each 10 msecs 300 times