If we have two or more anti-viruses installed on our PC, we might notice at times that one of them detects a virus in one of the files but other doesn't. Now the question arises, which one do you trust? Well, Anti-virus vendors may make you believe that they can detect anything and everything. It's true that most modern anti-virus softwares go beyond detecting traditional viruses. They detect trojans, track cookies and are even sophisticated enough to detect vulnerabilities inside compressed files and virtual disk images. But unfortunately no anti-virus is perfect. While some fail at detecting new vulnerabilities, others falsely identify a perfectly good file as infected. For that reason, it's not possible to find out which anti-virus software is at fault just based on the information provided. Our suggestion would be to read more about the virus, which the AV software mentioned is. If it's an old virus which has been studied for months or years, then it would be safe to assume that the file is really infected. If instead it was a recent virus, or if it's just a cookie or a hint of a virus rather than the virus itself, then you need to do more investigation. A good commercially supported anti-virus may provide a way for you to contact their support group which can help you troubleshoot further. In our opinion AV softwares backed by larger, reputable organisations usually perform better.