The text is a humorous jab at the rivalry between operating systems, specifically OS/2 and Windows. It plays on the concept of a virus scan detecting something harmful (like a virus) and suggesting its removal. In this case, the 'harmful' element is humorously identified as 'Windows', the competing operating system, rather than an actual virus. This is not a pun because it does not exploit different meanings of a word or similar-sounding words; it's a joke based on the context of software competition.
OS / 2 VirusScan - " Windows found : Remove it ? [ Y / y ] "