Almost 50% of the company pc was infected by virus, including servers. This DOWNAD.AD virus darn power! Even the most powerful antivirus I use is unable to detect or clean the virus. Additional tools are required to force Windows to delete the infected file.
Come across this site called UnLocker which is able to delete the stubborn virus.
Symantec also have a fix tool which is able to remove the virus. Click here to download the tool.