Its Google complaining beacuse it is seeing too much traffic from one IP address so thinks it is an attack, this is written simply so the average web user can understand it, hence the virus thing.
Part of the problem here is again NTLs proxys as that is the IP address that google is collecting (not looking through it to your address).
So it is not likely to be something wrong with your PC, just lots of NTL users googling.
Google should think about looking through the IP on the request lookup, but don't