Flagging legit web sites as suspicious does not prevent a virus. Get a decent anti-virus and an ad blocker for your browser.
Webroot is a decent anti-virus program according to various sources. It also marks web sites that have been proven to be unsafe in red. I don't visit red web sites.
These are the extensions that I have on Google Chrome:
Avast screwed up my old computer, so I didn't have an anti-virus program at the time when an old version of Firefox stopped working properly and wouldn't update itself:
Since Best Buy recommends Webroot, a lot of people are going to be using it, so if you find out that your web site is mistakenly marked as suspicious, just go here and get it cleared: