Callers with heavy foreign accents, possibly middle-eastern, will say they are from Microsoft and that something is wrong with your computer or that you have pornographic images that need to be cleaned.
The callers will direct you to a web site such as www.ammyy.com/en, http://showmypc.com or http://www.support.me. The caller directs you to download from one of those sites and give them a code. Once that is done the caller then is able to take over your computer.
The caller then asks for money in order to “fix” your computer. Some victims have had their computer rendered inoperable when downloading from these sites.
If you receive a call like this, please hang up. Microsoft does not make unsolicited phone calls for services. http://www.microsoft.com/security/online-privacy/avoid-phone-scams.aspx