Shutting down Problem? Maybe....

I am not sure if this is a hardware (i.e. BIOS settings) but I usually never shutdown my computer. I generally, put it on stand-by at night and allow it to shut down my monitor and that's all.
Ever since I got my new system, I have not been able to do this. I have gone so far as to make my power settings not shut anything at all down ever and to never go into stand-by; yet every morning when I wake up... there is no signal, fans are running, case lights are on, but the system does nothing until I hit the restart button. Then it restarts. I am at a loss. I have looked in BIOS and the only thing I cannot completely change is the S3 modes (there are only two and my only choices. In my Event Viewer I see that it shuts down any time between 3 and 4 every morning. I have checked all my scanners for a restart or shutdown after scan and found nothing. I am certainly scratching my head...

Any help or guidance would be appreciated. Thanks.

 

Hi Evan,

I read both links unfortunately they were both a little out of date. I am using XP but it is my secondary OS that I use for work. I have pretty much migrated to Win7 for everything else. I have already tried most of the solutions listed for vista. I am trying a couple of new things tonight, such as enabling wake up timers and setting up a wake up in BIOS for 7am (since I am usually not awake at that time). I figure it will at least be waiting for my password when I get up and if I get up earlier then maybe I'll find it's awake or not shutdown. The problem is that this messes with my Antiviral settings for overnight scans. If you find anything else that is pertinent to Windows 7, please post. Thanks.