Is USAntispy a virus?

Something called USAntispy has appeared on my computer. It appears in a pop-up window and won't close. It was not downloaded intentionally and I don't know of anything that was downloaded that it could have piggybacked on. It prompts "Repair" and "Register" only. There is Norton Antivirus installed and it's not picking up on this. A shortcut icon appeared on the desktop as well. I cannot find any files in which it is stored and I can't find any information online about this "virus". Does anyone know what this is and how to fix it?