Question Regarding Studio XPS 1645

I recently purchased a Dell Studio XPS 1645 and have one main question about it. I generally use my computer each day, and if I close the lid at night without shutting the computer off, in the morning the computer will be off. That wouldn't be a bad thing except many times it'll shut the computer off so I lose everything that was opened up. But the only weird thing is that it won't happen every time. I was just wondering if any of you have this problem and if there was some setting that I overlooked each time when I looked to change that. It's not a big thing, but I had a Dell computer provided by school and it would still be on in the morning after using it at night. Just got to be nice accessing everything quicker and not having to worry about everything being shut off. Thank you anyone who can provide any input on this.

 

Control Panel > Power Options > Advanced

 

Thank you very much. I looked in power options before when I made my own plan, but I guess that I must have never decided to go into advanced settings.