our pete williams has details. >> reporter: don holmes, a retired business consultant in arizona, says he was using his computer when a message popped up like this. a computer virus warning telling him to call for help immediately. he did, paid up. but the problem kept getting worse. >> i said, you know, i think this is a scam. and he just laughed d he says, you can't do anything about it. we're into your computer. >> reporter: he ended up having to buy a new computer, total cost $1,500. the justice department today announced a roundup of more than 260 people in the u.s. and overseas accused of cheating 2 million of them seniors, out fastest-growing scams. >> it's despicable because the people involved are vulnerable, and because of their stage in life, they don't have the opportunity frequently to recover. >> reporter: how to avoid it? don't fall for sudden claims that your computer has a problem. >> hang up on an unexpected call from someone who claims to be providing tech support. just hang up. it's a scam. >> reporter: and prosecutors say don't respond to another common scam, a cla