Do you have any antivirus/malware running on this PC? If so, make sure its running the latest engine and virus definition pattern.
Also, I would suggest that you download Malwarebytes and scan the computer. Malwarebytes does a pretty good job at finding malware on the system.
Download "Avast!", its free, its reliable and does not slow down your computer - Have you been downloading files with internet origin with Administrator account? I would suggest that if you get this virus off using "Avast!" (or command line if you have to D:) you must create a new user account afterwards (Standard, NOT administrator) and browse the web with that.
It is possibal that the obove ideas will not work if the virus has infected the computers protected files. When you run the AV it will clean up your system but when you reboot it will be back. If this happens please let me know and I will post a detailed way of getting rid of the virus.