Below is a copy n paste from another forum explaining the scam:-
I get these phone calls about one a week. Last time, I was ready for them: I had a machine set up with a clean XP installation, so I played dumb to see what they would do.
They pose as "Windows Support Centre", or suchlike, and say that they've been receiving reports from your computer that there's a problem. You'll probably be asked how old the machine is - however old it is, seemingly, you'll be told that the warranty on your Windows software has expired, or that you should have taken one out when you bought it. Then, you'll be talked though opening something called the Event Viewer, and shown a screen that contains a number of warnings and errors. They will tell you that this is serious, even to the extent that it's causing problems that might force your ISP to cut your connection and/or inform the police.
Let's stop here and make two points:
1. There may well be something called a "Windows warranty". However, I have been a Microsoft Partner for nearly a decade, and I've never heard of such a thing. I think we can assume that if such a thing existed, Microsoft would be sending me lots of information on how I can make money selling it. They haven't, because there isn't.
2. I've never seen an Event Viewer that didn't have warnings and errors, and I've been a Microsoft Certified Systems Engineer since 1999. Its function is to keep a record of everything that happens to the operating system so that people like me can find out what's happening if something has gone wrong. Most of the time, though, there's nothing to be alarmed about - in my case, most of the warnings were due to a printer not being found on the network because I'd switched it off.
OK, so the next stage is that you get passed to the "Technical Department". This is where it got interesting: I was told that a six digit support number was being generated so that my problem could be resolved, and I was directed to a website called logmein123, where I could enter this number. Now, this is a common tool used by people like me to fix machines over the network - clients call me with a problem, I can connect to the machine and show them what to do without having to leave my office. In this case, they were going to "fix" my machine. So I let them in. At this point, we will pause for a warning:
WARNING: DO NOT TRY THIS AT HOME ON YOUR MACHINE. I WAS GIVING THIS GUY COMPLETE ACCESS TO MY COMPUTER. HE COULD DO ANYTHING HE LIKED, TRANSFER FILES TO INSPECT AT LEISURE, ETC. I WAS USING A MACHINE WITH NOTHING ON IT BUT THE OPERATING SYSTEM. REPEAT: DO NOT LET ANYONE YOU DO NOT KNOW AND TRUST ONTO YOUR SYSTEM IN THIS WAY.
The first thing was that as soon as he connected, I could see the IP address he was connecting from, and I was able to trace this back to a company name, and trace the company back to its offices in Mumbai. While I was doing this (on another machine), I was watching a rather nasty piece of software being uploaded to my machine and installed. A bit of fiddling around, and I was asked to try running a few programs. Lo and behold, they all crashed with frightening looking error messages - remember, this was a machine that was working perfectly a few minutes before. This was explained as a consequence of the problems that I was having before, and that the diagnostic program they were running was now blocking programs that could get me into trouble.
This was the point at which I was asked for money - they started at £100 to fix the problem I already had, with an additional £80 for a simple one year warranty to protect me in the future, or if I preferred, I could give them £299 for an all-in package including fix, anti-virus software and a five year warranty. Visa and Mastercard accepted. If I didn't want to go ahead, then I wouldn't be able to do anything with it until it was fixed.
At this point I let him know what I was doing, complete with telling him the name and address of the company he was working for. I expected him to hang up on me, but he decided to argue with me, at one point telling me that I wasn't an MCSE and I didn't know what I was talking about. In the end, I just told him that if he had been in this country, he could expect to be arrested, and hung up on him.
So, in summary, I wasted my time in this way so you don't have to. If these pirates call you, don't say a word. Just put the phone down.