Be wary of these unscrupulous scammers! These guys do blind cold calling saying your computer is sending errors to them. They say they are mandated by Microsoft for support and want to help you *fix* your computer.
They also want you to get AMMYY to get inside your computer. Once inside, they show you your windows administrative logs which most know are ridden with warnings and errors that don't prevent windows from running. I've never come across a windows machine with a clean log anyways.
After showing you the logs they want to sell you their software to *fix* your computer. My neighbor, who is computer illiterate, almost fell for the scam, then said that he would have someone local look at it. At that moment, windows rebooted, and FAILED to start. When I looked into it, half of the OS and most programs was gone! Needed full format and reinstall to get computer up and running.
Google IMPCsupport scam and AMMYY scam for more details.