I have a new PC so I'm really new to using Windows Vista. Every once in a while, when I go to use it, after not having used it since the night before, I notice that it has rebooted. What gives? I have Windows' updates set to "download updates, but let me choose when to install them". I was looking through the Event Viewer and noticed something. There was Event ID 6008 that said "The previous system shutdown at 8:08:02 AM on 3/29/2008 was unexpected". I'm not sure if that means that there was a blue screen error or not. Can someone help me figure why it rebooted unexpectedly and if it was caused by a blue screen error? Thanks!

Go to Control Panel-System-Advanced System Settings-Start Up and Recovery Settings. Then uncheck the box Automatically Restart if it is currenty checked. That way, if it is a blue screen error, you will be able to right down the error message and post it here or search on google. Also, when you haven't used it since the night before, was it shutdown or put into sleep or hibernation mode ?

Ok, I went to Startup and Recovery and unchecked the box for it to Automatically Start. That led me to check to see if a MEMORY.DMP file existed in my Windows dir. It didn't so I must not have had a blue screen error. Also, I found where the Power Options is set and see that it's currently set to Sleep after 3 hours. Sleep in Vista is the equivalent of XP's Standby mode, right? If so, that doesn't quite explain why it had rebooted since I found everything closed out.

There are two sleep modes-S1 and S3(the deeper sleep state), as in XP. Of course there is hibernation, or S4. You can probably set which one is used(S1 or S3) in your BIOS. However, it appears that something is not allowing your computer to go into standby. You might want to update your video card drivers. A scheduled task, such as an automatic update for windows or antivirus software, can often bring a computer out of standby, though it wouldn't necessarily reboot.