HP dv6 laptop shutting down after 12-14 hours

I have a new HP dv6 laptop. The operating system is windows 7, 64 bit. I've had it less than a week. The power option I have set on it (default) calls for the system to go into the sleep mode after 20 minutes(closing the lid). I don't even see any option available to select that would shut the computer down after a certain time. The problem is, after having not used the laptop for approx. 12-14 hours, when I am ready to use it again, it has shut itself down. I don't know why it doesn't stay in the sleep mode.

Any ideas why the laptop is shutting down? It's not overheating because I keep it in a cool room and the air flow around it is not restricted.

Thanks for any help,

dmc

A computer will continue through a sleep mode into a hibernate mode if set that way. Hibernation shuts the systems down and may look like it is shutdown. To wake it up you may have to hit the power button, and it will say "resuming" and not require a password unless you have that set in the system.

My laptop will make some strange noises when it enters hibernation, like the fans speeding up and some lights coming on while it saves everyting to disk.

sg, maybe that's what it is doing. Although I don't see why. "Hibernate" is not listed on the power option plan that I have selected. I did notice one thing. I looked where the ventilation ribs were on my laptop. When I was setting it down beside me, I was covering the fan ventilation openings. Perhaps it has been overheating after so many hours and shutting down due to this. I'll find out for sure tomorrow when I come home from work.

Thanks for the reply and insight.