The latest SANS OUCH! newsletter (PDF) covers an increasingly-common scam in which the scammer calls their victim on the phone and talks their way into accessing the victim’s computer.
Here’s an except from the newsletter:
“You receive a phone call from a person claiming to be from a computer support company associated with Microsoft or another legitimate company. They claim to have detected your computer behaving abnormally, such as scanning the Internet, and believe it is infected with a virus. They explain they are investigating the issue and offer to help you secure your computer. They then use a variety of technical terms and take you through confusing steps to convince you that your computer is infected, scaring you into ultimately buying their product.”
SANS is a computer security company based in the USA. They publish several excellent newsletters, including OUCH! You can subscribe to any of these lists for free at http://www.sans.org/newsletters/.