Over the last few days I have had a number of calls from my clients who have a call from an a man with an Asian accent calling from Yorkshire saying that he is calling as a result of an email about the client having internet/spam/ISP problems. He claims to work for, amongst others, either Microsoft, Windows or "your ISP".
This is a spoof. Eventually he will invite you to pay an annual subscription of about £55.
The calls appear to be made at random to numbers listed in the phone book.
There is a site on www.techonsupport.com and he will give a phone number to call back on which is 01865 521065 - this is in Oxford. Clearly UK geography is not one of his strong points.
If you Google this URL or the phone number you will see a growing list of people asking about this - my advice is to have nothing to do with him - except if you are technical you could have a little game and tell outrageous fibs about your system and other fictitious details!