I found the following page and used the instructions people gave to make a sleep timer for my PC. however, now I find that every night at about 4:16am (I'd assume when the original timer ended) my computer shutsdown. I know its every night because I frequently put my PC in sleep mode and it always shuts down as soon as I wake it up in the morning. I deleted the .bat file a while ago so I know that won't fix this.
Here is the link:
http://www.tomshardware.com/forum/59073-63-sleep-timer-turn-computer-time
Here is the link:
http://www.tomshardware.com/forum/59073-63-sleep-timer-turn-computer-time