So you download a file to your computer, and your virus scanner comes up saying it’s a virus? There is a chance it may be a false positive.
It’s best to delete it, but if you think you need the file, it’s a good idea to run it through VirusTotal, a free service provided by an independent IT security lab, Hispasec Sistemas.
It is not a substitute for an antivirus program. It only scans individual files on demand. As well, some installers may have viruses inside, but if they are encrypted, they won’t show up. There is no 100% effective rate for detecting viruses.