Wonderful! That's the Windows Firewall started again - thanks so much for sorting this problem as I was getting close to the point where I'd thought I'd have to reformat and start again from scratch. I really appreciate this!
I'm not sure if I should create a new post for another issue which may be part of the same problem. Since the firewall went down, I've had no sound and have tried everything I know including new sound card and updating drivers, etc. As you can see from the attached image, Windows is reporting 'No Audio Device' yet the device manager shows them properly installed. (please ignore the exclamation mark at the HP printer in 'Other Devices').
I can't help thinking this is part of the same virus attack which have stopped the sound services. Could you advise please?