Turn on the PC while repeatedly pressing F8, go to Repair your Computer and run a system restore. I've found a lot of times a sys restore can fix the issue temporarily. Then afterwards run your anti virus/anti spyware(spybot, malwarebytes etc...) if you do not have an option for Repair Your Computer after F8, try the same F8 option and choose safe mode with networking. If the virus is still running, attempt to open task manager and and kill the process tree for it. If you cannot access any of these means, pretty much the 2 options are a live boot disc from an AV company or Portable OS, or like monu suggested, a complete destructive restore.