Its pretty common now days to get scammed from an I.T. “Professional” and some times not even with originally bad intentions just someone trying to do something over their own head or someone trying to scam you out of money or data.
If you watch this video you will see an unsolicited offer to clean this gentleman’s computer of malware but ends up holding the persons computer ransom, in a way. Dont fall for this stuff and listen to this guys advice. Its legit and simply ask lots of questions and expect clear answers and make sure you feel secure in allowing anyone to do work on your machine. No one should say they cannot do something without walking you through it and explaining in good detail and providing you with their information so you can validate who they are.
Watch, its interesting:
*Credit to Reddit.com where I found the video originally: http://www.reddit.com/r/technology/comments/u3yti/a_fake_antivirus_scammer_calls_a_security/