I have to update my iMAC at least once per week it seems. I can tell because I start getting the spinning beach ball when when I click on something. then I will chut down the system either by restarting or shutting down completely.
When it starts back up I get the black screen and an install white bar that says the system is updating.
iMac 21.5″ 4K, macOS 11.6
There are some questions which need to be answered. First, do you actually get a message that the system is installing an update. I think what you are seeing is the normal opening bar. Are you saying that when you click on something, that the computer shuts itself down? I would begin by doing the following things. Restart the computer in the Safe Mode. Hold down the Shift key on restart. Be patient. The process can take up to ten minutes. The Mac is fixing its operating system and cleaning its caches. Then restart normally and see what happens. I would also run Disk Utility in the Disk Repair mode. What does it say? Was something repaired? If a problem is found and remains, then rerun Disk Utility until the problem is cleared. Then report back with how things are and we can go from there.
I will do this immediately and report results...
Constant Updates
