I am trying to use event viewer and I am having trouble understanding all the jargon. I left for the weekend and came home today to find my computer restarted and with the prompt for my bios password up. How can I figure out when this happened? In event viewer what would indicate if the computer has been restarted or if someone was trying to enter a password? Please help me out.

Could anyone had gained access to the PC in your absence because this sounds suspiciously like a prank to me. Did you leave it switched on?

Yea I left it on with the prompt for my windows password up. When I came home the prompt for bios password was up. There was no power outages or anything like that all the clocks are showing the right time.

You didn't answer the first question, could anybody have got at it? I have to say I honestly can't think of anything else which could reboot a PC and bring it back up with the BIOS PW prompt. Have you got a cat pehaps....!!!! In the event logs you could look for event dates/times when you weren't there.

Someone posted this on another forum. Could this option restart my computer? Also what would be the phrase in event viewer that indicates when the computer shuts down and starts up? select Start > Control Panel > Settings > System (in the Classic-style Start menu, Control Panel is under Settings). Click Advanced > System And Recovery > Settings. In the System Failure section, clear the Automatically Restart check box, then click OK.

u can filter the event viewer, filter the security, and then search for the date, users.............. and then u´ll see what could happened..

Irrespective of whether Automatic Restart was enabled or not it still would not cause the machine to come back in the BIOS. Also you didn't answer my question: "Could anybody have got at it whilst you were away?" but your comment "what would indicate if the computer has been restarted or if someone was trying to enter a password" clearly suggests so and I would guess you're trying to pin down when and thus possibly identify who. Every PC will show different things in it's logs but as good an indicator as any is the timing of events in Application where any programmes you have running on startup, such as antivirus and the Windows Security Center, should show up date & time stamped at boot time.