My PC has been randomly rebooting every 45 minutes or so. A warning pops up telling me I have a minute to save my work before the computer shuts down. Before it does this, Norton detects a backdoor virus...but I have run a full system scan and it doesn't find anything. My knowledge of computers is limited because my dad usually helps me but it's 3AM and I'm trying to pull an all-nighter so I could really use some help. Thanks!