No driver on Cubase artist 7.5

Cubase Artist 7.5 suddenly could not find a driver when I checked VST devices. I happened to check the old version of Cubase artist 7 on the same computer and the drivers are there. I tried re downloading Cubase Artist 7.5 and it didn’t help. Any suggestions?

Have you done a virus scan?

Thanks for replying. I use Norton 360 and it found nothing. I ended up looking at the Microsoft site and downloaded the free security program they offer and that did find a powelik virus. Once it was removed the drivers came back. Thanks again!!