I've been sort of waiting for a call like I received yesterday. I've heard about them, and even know a few people who've been taken in by them, but until now I've never experienced them myself. And whilst I would have loved the opportunity to bait the caller a little, I was supposed to be working from home and couldn't give them as much time as I would've liked.
The call was from a woman with an Indian (Asian?) accent telling me that she was calling from Windows about a lot of 'Critical Errors' they were seeing on their server from my computer. Right away it's clearly a scam - an unknown company is seeing errors on my computer how? And which computer? On my network there could be up to 20 devices connected at any time, about 6 of these are what would be commonly referred to as 'computers'. So despite the huge temptation, I only asked them which windows they were talking about, double- or single- glazed and then proceeded to inform them that they couldn't be seeing any windows errors as my computer didn't use Windows.
The modus operandi of these scammers, is to get you to fire up the Windows Event Log viewer (where there will be a number of errors, but mostly normal under every day running of a Windows PC), prove to you that you can't delete this error (hmm, it's a log file) and then inform you that they are caused by un-deletable viruses which only they can remove. They'll use a remote-control service such as TeamViewer and get you to give them control of your PC. And, of course, they're not doing this for free.