My son worked for a computer repair company for a few years. He told me that they had a huge amount of people bringing their computers in because of one similar scam that was going around. He said that they would get a call from someone claiming to be with Mircosoft and that they detected a problem with their computers. They would gain access to all the files within the computer and then lock it up so that the person wouldn't be able to even log on.
Seriously terrible to prey on the elderly. I'm glad your parents have you to help them out with this sort of thing.