The Windows Profile Service service failed the sign-in. User profile cannot be loaded.

I've been using Windows 11 on a new PC since 22nd November last year. Everything was fine for a month, but when I started up my PC on 26th December, I got a black screen with the message in the title. When I continued, instead of the usual Windows Spotlight images and widgets (not sure if I'm using the word correctly...I mean the trivia and promos), the login screen had the default wavey blue background and no widgets. I shut my PC down, started it up again and had the same problem, so I tried logging in this time and it entered what I assume is safe mode. I shut down and started up my PC again and had the same problem, but after logging in this time, I decided to restart my PC rather than shut down and start up. That solved the problem for a week, but on 4th January, it happened again. As before, logging in and restarting fixed it, and it's been fine for the last couple of days.

Another issue I've noticed since then is that my Windows Spotlight images and widgets stopped changing on a regular basis. The background was stuck on an image of Shanghai. Today, I tried clicking the option to move on to the next image, but now the widgets are gone and it's stuck on the wavey blue background.

Although I've been able to log in and use my PC as normal for the most part, I thought I should ask for help before the problem grows into anything more serious. Any help you can give would be greatly appreciated.