This is the latest form of scare scam, and this is how it works..
A person calls you up claiming to work for Microsoft or some security software company, and tells you that your computer has been monitored and been found to contain a mass of virus infections. The person will ask if you will allow a remote connection such that it can be fixed. You will also be asked for payment which will cover you for a year or maybe two.
Let's get something straight.
The ONLY company likely to contact you with scare stuff like the above is your own ISP. They will not call you, but they will send an email advising you to ensure that you have proper protection from computer virus infections, and most likely offer you at NO extra charge their own online protection.
Microsoft do NOT have your telephone number and don't have the time or personnel to call you even if they did have it. The same applies to any other bona-fide company.
If you get a call like the above, before you say anything, place the receiver firmly down on the base and cancel the call.
OK. Do you get the message? The above advice will save you anything up to $300 and a lot of embarrassment.
The official Microsoft website on this topic.
If you complied with the caller's request..
It is difficult to say what changes the 'caller' may have made.
One change sometimes seen is to the Windows login password. Yes, you have guessed already that you will be locked out of Windows. This is a particularly nasty one.
Another may be the installation of utilities designed to pick up on password entry. This is very useful if you do online banking. The computer may well be set to 'phone home', not your home, with the information.
The last point is all about giving your credit card number to the caller because he wants to charge you for a year's free support that you will NOT get, and for his time 'setting you up' for a fall..
If you have let the caller have access to your computer, you need to get your completely wiped and re-installed at your earliest convenience. This will negate anything that the caller may have changed or added.
You have been warned..