After latest update pc automatically shuts down after a while

After the latest update my pc automatically enters sleep mode and, if left alone shuts down completely after about an hour.

In system settings I was able to find the sleep settings and reset the monitor time-out to 'never' and, I think, hard-drive sleep to 'never.

This solved part of my problem in that it no longer goes to sleep.

However, I like to keep my pc running with programs such as Outlook minimized so that I will receive incoming emails, etc.
When I leave my machine to go and do some other work it is incredibly frustrating to come back an hour later and find that everything has automatically shut itself down and I have to restart the whole shebang, which takes considerably longer that a normal start-up.

Can anyone tell me where I can find the settings to cure this?

After 91 views still no suggestions.

Anyone got any ideas, please?

Well, it appears that the problem has solved itself after the latest update. :)

It's not doing it any more. I still would have liked to know what originally caused this though.