They can also come from legitimate sources too. Most websites deliver content from multiple servers, sometimes over a dozen different ones. Any one of those can be compromised and set to deliver malware. While these are often caught within minutes, to make a blanket statement that viruses only come from questionable sites is just wrong. I've been using computers since long before the Internet and have even built them by hand with a soldering iron. In my 30+ years of working with PCs, the only time I've ever been infected was when I had forgot to turn my A/V back on after some testing. So, personal experience is extremely variable and for most people, practicing safe computing isn't something they think about. This is why these people NEED an A/V solution. Whatever A/V solution you use, I recommend against ANY that are subscription based. These companies have a vested interest in having their software pop up a message every now and then claiming they've protected you from some unknown bad guy. This is how they get you to keep paying for the subscription every year when there are perfectly usable FREE solutions out there. Personally, I have been using Avast for many years and have never had it cause a problem. The issues with KSP and Avast are related to having the game installed in Windows protected folders. Since KSP does not have a proper installer, files copied to these windows managed folders do not get the proper permissions set and Avast might think something funny is going on in your system. This is always solved by moving the program to somewhere like C:\Games\KSP. Cheers! Capt'n Skunky KSP Community Manager