Determining if and how outside forces are causing the customer's problem takes a bit of investigative work. The first step is determining if an outside force is causing the problem. We'll use a fictional accounting software program as an example. The problem as it's sent to you is "after I installed the software, my virus scanner said I had a virus on the computer."
Let's first look at where the customer obtained the software. You ask questions like "where did you get your copy of the software? Was it directly from us on a CD? Was it via a web link?" The goal is confirm the software installed did not come from a questionable location such as some pirate software site or from another customer’s computer. As long as the location is a "safe location" then that leads to one of two possibilities; either your business has a virus packaged in their software or it has something else to do with the customer. It’s easy to eliminate the first option so it's on to the second.
At this point, you know the user has installed a clean copy of the software but is getting a virus notification. You now know that an outside force is at work, but how?
More on this later...