She believed that the indian on the phone was from Microsoft and somehow detected that her computer (and every other computer in the house, including the 27" iMac I bought my mom for mother's day) were infected. They pinched her for $250 bucks per machine ($750 total). Gave them her credit card number. Let them install shit on the machines. Everything.
Even after I called her and explained to her what just happened, she took a ton of persuading to cancel her credit card (I don't even know if she ever did that), because she was STILL worried that despite what I (a software engineer of two decades) told her, it "might still be legitimate".
Also, who calls back numbers they don't recognize? If you're a number I don't recognize and you don't leave a voicemail, then fuck you!