How do you know if your computer has a virus?

I was using the Norton Internet Security program and as I was scanning for virues, my computer kept making sounds. I have Windows Vista, do you know the sound when the computer's about to shut down? My computer kept doing that and it also kept freezing while it was making that sound. So do I have a virus? The Norton scan told me I don't. How can you tell when your computer's infected?

How do you know if your computer has a virus?suzuki

Scan your computer with an online anti-virus scanner. BitDefender or TrendMicro are two of the best that will allow you to clean or remove the virus.

You also need to get anti-spyware. I recommend using Ad-aware and Spybot (they are free). Other great free anti-spyware programs would be Super anti-spyware and AVG anti-spyware (formally Ewido).

I strongly recommend using FireFox, it's a far better and safer alternative to Internet Explorer. If you add-on McAfee SiteAdvisor, it will warn you of potentially harmful sites. I also recommend CCleaner which is a free system optimization and privacy tool.

How do you know if your computer has a virus?virus

Without anti-virus software, you really can't. The worst malware ("virus") is specifically designed to do it's dirty deeds (identity theft, zombification, etc) steathly and silently without the user suspecting a thing.