My PC used to be on 24/7 until I decided that I wasting power however now it seems to want to close down at 23:15 unless it is actually working on something - This is annoying me and I would like to know what is causing this shutdown - does anyone have an explanation?
You could try unticking 'allow this device to wake the computer' which I know is different to shutting it down but it could bear some relation. I'd also try running a virus/malware scan and also check your bios to see if anything related has changed in there (sometimes there are timer settings in the bios).
I checked the power options and under Sleep I only have two options - Sleep after which is set at Never and Allow wake timers which is set at Disable - no other options as per your pic!
Any other things i might look at?
Hmm.... Try checking your scheduled tasks and the settings highlighted in the screenshot as sometimes these can mess with your computer waking up or turning off
I seem to be a little confused. Your system used to run 24 hours a day. Now it is turning after 23 hours and 15 minutes, or it is shutting down at 11:15 P.M.?
The only thing I can think of that has an expiration date is a lease on a network connection. Don't know why that would shut the system down, unless some type of conflict was occuring.
Any parental controls involved?
There are some performance troubleshooters, you might try one of those.
Hopefully, you will find something in the Task Scheduler as Kemical suggests.
You could try unticking 'allow this device to wake the computer' which I know is different to shutting it down but it could bear some relation. I'd also try running a virus/malware scan and also check your bios to see if anything related has changed in there (sometimes there are timer settings in the bios).