9 Replies Latest reply: Nov 27, 2012 3:00 PM by BDAqua
roverbill Level 1 (0 points)

I have a Mac Mini (OS X 10.6.8) that has started freezing with a solid grey screen on boot up (i.e., no Apple logo, no spinning wheel). The work around is relatively easy: all I need to do is disconnect the USB cable running to my ATEN KVM CS1768 switch, power down, power up and then reconnect the USB cable once the Mac desktop is loaded. While this just happened three times in a row, it doesn't happen all the time. The first time it happened last summer I spent an hour on the phone with Mac support (the computer was still under warranty at that point) and the very last suggestion they made was to disconnect the USB cables before attempting to reboot. (I don't recall precisely if the problem occured when my USB peripherals-- a Mac USB keyboard and mouse-- were directly connected to the Mini rather than being routed through the KVM switch, but I *think* it did.)


If anyone has a quick answer or can point me to a prior discussion of this same (or a related) issue, I would be most grateful

Mac mini, Mac OS X (10.6.8), Client Version
  • BDAqua Level 10 (122,286 points)

    Hello, sounds a bit like a short or ground loop in some USB device/cable/power supply.


    Open console in Applications>Utilities, check the system log for the date/time of the last problem  & the Startup right after that for clues.

  • roverbill Level 1 (0 points)



    Thanks for the response. I've been using Macs for a little over four years now but this is only the first time I have gone to the system logs (or any of the other logs available from the consolute utility).


    The system log appears to be completely unhelpful. I got up this morning sometime after 6:00 a.m. and posted my first report (see above) at 6:48 a.m. (I don't have a record of the exact times of the boot up freezes.)


    Following are the *entire* contents ot the system log covering this period:


    Nov 19 01:12:15 WHW-Mac-Mini loginwindow[40]: loginwindow SleepWakeCallback WILL sleep

    Nov 19 06:26:35 WHW-Mac-Mini loginwindow[40]: loginwindow SleepWakeCallback will power on, Currenttime:11/19/2012 6:26:35.019 AM - Waketime:11/19/2012 6:26:33.980 AM = Deltatime:1.038853049

    Nov 19 06:27:05 WHW-Mac-Mini loginwindow[40]: no spins reported for this wake

    Nov 19 07:35:13 WHW-Mac-Mini login[17714]: USER_PROCESS: 17714 ttys000


    I assume that one of the two successful reboots that I did during this period was probably at 6:27.


    The "all messages" log has some additional information from this time frame that may be  useful:


    11/19/12 6:26:35 AMkernelWake reason =
    11/19/12 6:26:35 AMkernelSystem Wake
    11/19/12 6:26:35 AMkernelPrevious Sleep Cause: 5
    11/19/12 6:26:35 AMkernelEIR is supported.
    11/19/12 6:26:35 AMkernelSSP is supported.
    11/19/12 6:26:37 AMkernelAppleBCM5701Ethernet:    0    1 BJP firmware wakeup: service connect
    11/19/12 6:26:37 AMkernelAppleBCM5701::selectMedium - autoselect, any duplex, flow control allowed
    11/19/12 6:26:37 AMkernelEthernet [AppleBCM5701Ethernet]: Link down on en0
    11/19/12 6:26:38 AMkernelEthernet [AppleBCM5701Ethernet]: Link up on en0, 1-Gigabit, Full-duplex, Symmetric flow-control, Debug [79ed,0f00,0de1,0300,c5e1,3c00]
    11/19/12 6:26:39 AMntpd[28]bind() fd 25, family 30, port 123, scope 4, addr fe80::c62c:3ff:fe1f:4f7, in6_is_addr_multicast=0 flags=0x11 fails: Can't assign requested address
    11/19/12 6:26:39 AMntpd[28]unable to create socket on en0 (17) for fe80::c62c:3ff:fe1f:4f7#123
    11/19/12 6:26:40 AMconfigd[15]network configuration changed.
    11/19/12 6:26:43 AM/System/Library/CoreServices/RemoteManagement/AppleVNCServer.bundle/Contents/Mac OS/AppleVNCServer[140]Authentication: FAILED :: User Name: N/A :: Viewer Address: :: Type: VNC DES


    Following this there were quite a few unsuccessful attempts to connect with my VNC server and little else that seemed noteworthy. Nothing that referenced anything to do with USB or USB peripherals.


    And, of course, when I rebooted just now (in the hopes of getting a report from all of the logs corresponding to the exact time of the reboot), my Mini started just fine with no freeze up.

  • BDAqua Level 10 (122,286 points)

    Next time you get a gray screen... with a bright light see what is going on in the screen.. (is a bit tricky to see, but works in a 45 degree angle).


    Ya know, it's sounds related to this problem...


    I wonder if it's a variation of this, of which I've seen many different symptoms...



    Move the mouse or trackpad cursor over the center area of the login window so you can see the user icons. Click on the icon of the user that you would like to login as, type in the user's password, and press Return.

    If the login window is configured to show only the name and password fields, type in the user's name and password into the fields, and press Return (even if you cannot see the rest of the login window).

    Additional Information

    This issue will not occur if the display is not sleeping when the account is logged out. Use the steps below to confirm that the account is not configured to log out automatically while the display is sleeping:

        1.    Open System Preferences > Security & Privacy > General.  Click the padlock to unlock the preference pane and enter your admin password. Click the Advanced button at the bottom, then see if the option "Log out after N minutes of inactivity" (where N is the number of minutes) is enabled.

        2.    Open System Preferences > Energy Saver and configure Display Sleep to occur after the account is logged out, by dragging the slider to a number of minutes that is greater than N was set to in the previous step.

    Important: If automatic log out is not needed, disable "Log out after Nminutes of inactivity" in System Preferences > Security & Privacy > General. This will also prevent the issue.



  • roverbill Level 1 (0 points)

    I am the only user; I have automatic login; I never log out or turn it off except when I shut it down to reboot. Of my six computers on the KVM, this is my day to day workhorse and the one computer that I usually leave the KVM set to. This means that having the display sleep is key to maintaining monitor life and saving energy. (My prior monitor-- a VX2835wm-- had never gone to sleep properly which was the subject of my one other thread at this site; my new monitor-- a Dell U2412M-- goes to sleep properly most of the time now which convinced me that my Mac Mini wasn't the cause of my earlier problem.) One of the many reasons I need to keep my computer running (and logged in) is that in addition to needing a live connection to my Apple TV, I also use the postfix server in the Unix portion of my Mac to send out log and report emails 24x7 from LAN side appliances such as a printer and an NAS device. So... I will try the trick with the bright light the next time there is a problem. I will also check to see if bypassing the KVM by attaching my Mac mouse and keyboard directly to the Mini's USB ports does anything... and I'll report back.

  • BDAqua Level 10 (122,286 points)

    OK, good plan, & good luck.

  • roverbill Level 1 (0 points)

    OK, so I had my Mac Mini freeze on the grey screen once again. I unplugged my USB cable and rebooted.  Even though the USB cable was unplugged, the computer froze once again on the grey screen. This time, however, while the computer was frozen in front of me, I got interrupted by a phone call. While I was talking on the phone, after more than a minute or so had passed, I notice that a small grey circular picture of the earth appeared and that it flashed on and off several times for a minute or so at intervals a few seconds apart. Then that stopped and the normal boot up of the operating system happened. Because I was on the phone, I repeated the boot up process, this time with the USB cable to my KVM plugged in and this time with a digital camera present. I've attached a screenshot of the flashing image that I saw. (It was flashing fast enough that I only caught it once on two tries.)


    At a minimum, can someone tell me what this image on boot up indicates? I have never seen it before...DSC_0003.JPG

  • roverbill Level 1 (0 points)

    Here was my server log from the time of the first boot failure through to right before I opened up Gimp to resize the image shown in the immediately preceding posting (after I had successfully, albeit slowly, rebooted the second time).


    [Deleted, see immediately following message.]

  • roverbill Level 1 (0 points)

    Mea culpa: I now understand that this latest report was caused by my inadvertantly having turned on the network boot option. Given that I only discovered this feature five days ago when I was using my wife's Macbook (and subsequently checked it out on my Mac Mini at which time I must have changed the setting without realizing it), the two prior posts can be ignored but I am still searching for an answer to the USB related boot problem which I originally related. (In a way I am glad since this latest false flag was completely independent of whether or not my USB cable was plugged in which made the explanation suspect.) I apologize for not vetting my two prior posts more carefully but I jumped the gun in thinking that I had a recurrence of my original problem.

  • BDAqua Level 10 (122,286 points)

    Great, you found it, that is the Net Boot globe... looking for a Server to boot from!