Would like my PC to shutdown rather than go to sleep

As it is now, my PC goes to "sleep" after 30minn. idle, but every so often i can´t start it again when its been in sleep mode and have to reboot the PC.. so I´d like to know if maybe it would be possible to make the computer "shutdown" after a period of idle, rather than it goes to "sleep" ? (Hibernate is not what I´m looking for)

Perhaps some sort of registry editing/setting could change the behavour of what "sleep" does, (in this case shuts down the PC instead) could be a solution?...
I dont know what to edit/change if it´s possible, so any help would be much appressiated...

That doesn't sound like a very good idea, what if you are on a phone call or eating your dinner and have a game running or file open that you haven't saved, would having your computer shut down like that become very annoying, why not just disable sleep and just have your monitor turn off or have a screen saver, so when exiting the screen saver it locks the computer and puts you on the logon screen.

I dont use the PC for any important work, it is mostly used for gaming and surfing the internet... but often I go away to do other things and then I forget about it running untill maybe next day, so I would rather have it shut down by itself after a while than have it running all night...

Use the BIOS to set your on and off times, if such a setting is available (I know modern Phoenix BIOSs usually have this, and ISTR that Award does also....

Unfortunately, that is only for a set *time* not after a period of time, but it would do you well if you have left it on overnight....