IDG Answers is a community of experts who are passionate about technology. Ask a question or answer one below.
It sounds like an advertising pop-up disguised to appear as if a virus is active on your machine. I've seen similar pop-up ads before. Think about it, if it really was a virus or malware, who would design it so it was so obvious and threatening. That would defeat the purpose of the malware. But you should still follow Christopher's advice to be on the safe side.