I have a fresh installation of Windows 11 which after a few weeks' use has started flickering and not responding for a few seconds, and this happens every few minutes. On occasion I get a beep then flickering.
Windows task manager doesn't flicker, which means (according to MS) it's not a display driver issue but an application.
So all day today I've been closing down each application in turn, and it turns out Dropbox was the culprit. As soon as I shut it down, Windows behaved normally.
I started it back up again, and found a 5 year old forum post here that turning off the Dropbox badge in Preferences would help (on a previous version of Windows of course). So far this seems to have done the trick.
I am wondering if this is a known error or something that anyone else has noticed?