Avast says no virus but
 

our PC goes back to the log in screen now and again like someone restarted it. But no one has.

Is this a symptom of a virus that is using our computer for nefarious deeds?

Does it do it while you are in front of it working or is it after a period of inactivity?

Never seen it do it. Used it last night. Just went to use it again, it was on the Dell welcome screen to input your password.

has done this several times in the last 6+ months. It is used sporadically.

how old is it, maybe the hard drive is going

Hal, "Dave, my mind is going."

computer is about a year old. it's new.

You sure it's not logging out due to inactivity.

They do that.

Check the settings for power, user activity, hard drive parking and such to see if he timer is set to something like 1 minute or very low. We used to do that to a secretary years ago who was really mean and when she'd leave her PC to get coffee or raise hell with somebody one of us would quickly change the screen saver to 1 minute. Then one of us would try to log into the network with her login and fail on purpose then her account was locked so when she came back she could not get started to work. She then would call support and raise hell with them..........

Windows Updates? I wonder if it's downloading updates at night, some of which require a restart. Depending on your settings, the restarts can/will happen automatically (with a countdown timer) if you are not there to click the "dismiss" or "remind me later" pop-ups.

I think it is this.

it's probably the updates. it's always updating, or asking to be.

thank you all.

There was a Windows update yesterday. They always require a reboot.