I simply tell them 'there is nothing wrong with my computer
Jocork; I remember being told by someone who is far more IT savvy than me, never speak to any of these "callers", even though they are probably robots as they can extract words , even a simple "yes" or "no" in your voice and use in another context. 
I use an answering M/c; robots or similar ring off as soon as my "Welcome" fires up, legit callers can be intercepted by picking up the hand piece, or leave a message. Almost everyone I know uses a mobile for everything, but being a Luddite I'm still hanging on to my landline. 