most likely a fake virus warning, quite likely your only infection is that program that displays this warning ... it will scam you into paying for their "anti virus" and in the meantime it will only infect you more and more with some serious trojans and backdoors etc
download this program, make sure you have their newest malware definitions and run a full scan
http://www.malwarebytes.org/
if it gets rid of it, you're lucky, but make sure you have a good real time antivirus and firewall on your machine