Ninja Pendisk is a free program to guard computers against viruses transmitted by USB pen disks.Ninja Pendisk sits quietly in the tray and waits for a USB drive to be inserted. When that happens, it will scan the drive looking for known malicious files including autorun.inf and ctfmon.exe to name just a couple. You will then get a status screen of what it did. That's it.While we're not fans of most programs that run on startup and in the system tray, we noticed Ninja Pendisk uses almost no CPU and maybe 6MB of RAM.A text file is created on the first run, and it contains all the files it will delete, options, and more. For example, the options read like this:[options]no_minimize=0Disable_AutoPlay=1Auto_Clean=1evil_ninja=0As you can see, it's self-explanatory so that you can edit options to your liking or add and remove files you want to be deleted when found.Finally, it's easy to overlook is the ability to find more options by right clicking on the tray icon. You can view your current configuration, LAN chat, visit the homepage, add to startup as well as check or uncheck auto clean and autoplay.Of course, you might be wondering- why? You can always run it as needed, but one good use for Ninja is computer techs. Most techs keep a thumb drive with all the tools they need and often have to update it meaning they are plugging it into their computer over and over again. Since techs then bring their thumb drives to repair computers, carrying a virus or malware on your USB drive should be a concern.