CHARLOTTE, N.C. - Jennifer Janszen was having trouble with her new laptop that she bought during this past holiday season. So when a "Windows tech support" rep called, she figured Microsoft was just trying to help her out.

"I truly believed it, because my computer hasn't been working correctly," she said.

The rep told her to log into a website where he could fix her PC.

"I let them go into my computer, where they could do anything inside it," she said.

But Janszen says the caller suddenly said she needed to pay him $300, in the form of gift cards, for his help.

"You need to go to Walmart and get the iTunes cards from Walmart, in increments of hundreds and fifties," she says he told her.

She realized, at that point, that she had just been scammed.

Scammers Slicker Than Ever

What makes this scam so convincing is that the caller is so professional. He'll tell you to log onto your computer, so that you will see what he is talking about.

"They actually had me go in and push the Windows button and type some things, and there was a screen that popped up where they showed me a thousand errors and hackers on my computer," she said.

It's sometimes called the Microsoft Scam, the Windows Scam, or the Tech Support Scam. No matter what it is called, it's important to know that Microsoft will never call to say it found a problem with your PC. Its staffers are not monitoring millions of computers for problems.