This isn't new but some people may not be aware of it. You may get a phone call from someone purporting to be from Microsoft who says that your ISP has been aware of a problem with your computer and passed the problem onto them. They will ask you to type something in then very quickly be controlling your computer showing you all the things wrong with it and try to get you to buy some software. Unfortunately a friend of ours did just this, the computer had become very slow and internet access had become almost impossible so it sounded plausible and she agreed to follow their instructions. Fortunately she didn't buy any software from them and soon realised she was being scammed and shut the internet down. The computer wouldn't shut down. After being in contact with her bank and the ISP it looks like she has escaped being conned but it has left her quite upset. I've rebuilt her computer so that there is no trace of the malware I found. Please be careful don't let these scum catch you out.