Over the last couple of days, I’ve repeatedly had a dialog box appear for a fraction of a second and then disappear, much too quickly to read the contents. It’s happened maybe 4 or 5 times so far; it comes unexpectedly, not apparently prompted by any action I’ve taken; I’ve been in Safari each time it happened, but on different websites, and it’s seemed more like another application momentarily stealing focus rather something from Safari or an open website (e.g. it appears centered on the whole screen, not on the Safari window); I spend much of my time working in webapps, so being in Safari just by chance each time isn’t unexpected. It’s occurred on two different devices (home laptop and office desktop), running different Mac OS versions (Ventura 13.6.1 and Sonoma 14.1.1), but under the same Apple ID.

How can I even begin to diagnose this? As I understand from Googling around, such flash-up dialogue boxes can sometimes be caused by malware, but equally by legitimate software (e.g. auto-updaters for installed applications). I’ve done the most basic safeguards against malware (all OS security updates installed; checked that all listed login items + background items appear legitimate), and found no red flags. But I’d really like to know what’s going on! Is there a log file where I can check through recently-appeared windows/dialogs, active apps, etc, or anything like that?


1 Answer 1


Follow the instructions here on taking a video capture of the screen. Once you have a capture, play the video frame by frame until you can see the popup. Then report back.

  • 2
    This is good and we might even be able to point other questions here once confirming this approach can catch such irritating and concerning behaviors.
    – bmike
    Commented Nov 10, 2023 at 14:59
  • 2
    If the native screencapture isn't fast enough to capture this split-second flash, there are apps such as Screenflick that can capture at up to 120fps.
    – luckman212
    Commented Nov 11, 2023 at 18:38
  • 1
    I have the same thing, but I don't use Safari - Firefox Developer Edition.
    – user254694
    Commented Nov 13, 2023 at 9:04

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