MBP 13" 2016 Sierra 10.12.6 - intermittently a grey login screen appears with a blurred smudge that moves every few seconds to different parts of the screen. Entering login password opens up computer to desktop as usual. Hacked? Virus? Scanned with Norton and shows no infections.
Try booting into the Safe Mode to see if you see the same thing.
Safe Mode - About
Safe Mode Startup – El Capitan. also Sierra
If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.
I do tech support for a living. Here are the steps you need to take. If you need help call Apple at 800-275-2273 between 8am - 11pm (may vary on holidays) or go to getsupport.apple.com and follow the prompts to setup a call.
1. Do a backup (unless you don't need to back it up)
2. Make sure you know your Mac's login password and your Apple ID & password.
3. Wait until the issue happens again and note the date and time of the issue (HH:MM:SS if possible)
4. Reset SMC. Look up article HT201295 on apple's website for help. Test the issue afterward. If it's gone, keep an eye on it and notate the date and time if happens again then contact Apple (see instructions above)
5. If it still happens after resetting SMC contact Apple (see instructions above)
Thank you Eric, however this screen comes up intermittently and I cannot force it to happen. I have not been able to figure out what brings up this screen, it just shows up once every few days or sometimes a week goes by.
Thank you Jeremy_v, I do not have a dynamic background but have opted to change to one of the Apple backgrounds and screen savers since I did have a picture of mine as the background. I also tried MacOS recovery but the gray sceen that comes up is not the same as the one with moving image, and did not show any moving image as when the issue occurs. Will see if the change of background affects this issue. Cheers, Chris
If everything checks out with your desktop photo, it might be a good step to try booting into macOS Recovery next. This will give you a similar-colored grey background and you can see if the same behavior occurs there. You'll find the steps here, in the article About macOS Recovery .Change your background
You can change the picture that's displayed on your Mac's desktop. You can choose one of the desktop pictures that comes with your Mac, a solid color, or one of your own pictures.
- Click the Launchpad icon in the Dock, and then click System Preferences. If you're using Mac OS X v10.6 or later, click the System Preferences icon in the Dock.
- Click Desktop & Screen Saver, and then click Desktop.
- To select the kind of desktop picture you want to use, do one of the following:
- To use an image that come with your Mac, select a folder under the Apple section.
- To use a solid color, select "Solid Colors" under the Apple section.
- To use your own picture, select the Picture folder under "Folders," if the picture you want is stored in your Pictures folder. If your image is in another folder, click the Add button (+), then find and select the folder that your picture is in. Then, click Choose.
- Select the picture you want in the box on the right.
After you test to see if the same blur appears, and the macOS Utilities screen loads, you can back to normal by clicking the Apple menu () > Restart.How to use macOS Recovery
Hold down Command-R or one of the other macOS Recovery key combinations on your keyboard immediately after pressing the power button to turn on your Mac, or immediately after your Mac begins to restart. Continue holding until you see the Apple logo or a spinning globe.
You are welcome. Link to suggested Apple Support article.
Reset SMC
blurred image moves on login screen
