Windows 7 mysteriously restarting

[VirtualLarry]

Friend's computer, running Win7 64-bit HP, on an AMD Athlon II X4 3.0Ghz, 4GB RAM, SSD, etc.

Anyways, he has been having issues with occasional black screens, and had to press the reset button.

Just a few minutes ago, he said his computer restarted on him.

Not a power-glitch type of restart, but it went exactly if he explicitly selected "Restart" on the power-off options menu.

Why would Windows 7 restart on it's own like that?

Is there a strong likelyhood of a remote-access trojan?

 

[mikeymikec]

Check the event log at the time of the restart. I wonder whether something more innocent happened like Microsoft pushed an urgent automatic update, and when he pressed return/space while typing something, the message appeared, grabbing the focus while he was typing.

I assume he wasn't installing anything at the time that may have asked him to restart and a similar scenario to what I just described happened.

 

[VirtualLarry]

Friend told me that it happened, when he went to a movie-watching site, and clicked on the outer part of the page like he usually does. Apparently, the site normally launches a pop-under ad, but that time, it shut down and restarted his computer.

I remember when I got hit by some exploit browsing pr0n on my XP box, after coming home from vacation (no updates!), and command-prompt windows started popping up everywhere.

I'm pretty convinced it's some sort of trojan/botnet, and needs to be reformatted.

Edit: I installed and ran Malwarebytes, and it found "Trojan.Agent" in C:\Windows\svchost.exe. I think that file is normally in windows\system32.

I told my friend that it is no guarantee that everything bad is removed, just because malwarebytes says it's clean.