Please be aware that we are seeing a high number of scam phonecalls at the moment. These usually consist of people claiming to be from Microsoft or other large IT companies claiming that you are infected with all manner of malicious software. Whilst this may indeed be the case they are lying as there is no way to tie your computer to your phone number to your name legally without a court order.
These people are persistant and feel free to be rude but never never let them control you PC – you will regret it. If they ring hang up do not try to prove they are a bona fide service as they are very plausable.
The average hit for this scam in the uk is around £150, not a small sum in these lean times, be vigilant.