Received three calls in the space of a week from this phone number. Each time I answer the caller hangs up. Annoying!

They're still doing it with the same number. For me they called themselves esolving.com

recieved a call from them "Online PC Care" on 17/10/2011.
They tried to get me to make system adjustments on my computer

This phone number was given to me by a cold caller claiming to be Brad Wilson from the "Global Computer Maintenance Department" of "Online PC Care" to perform my "Microsoft Windows Maintenance".

Brad had me access several log files on my PC and showed me a "hidden directory containing malicious file downloads". After accessing one log he actually spat out an "Oh, God!".

The logs and directory all contained benign information that is stored as part of my PC's day-to-day functions.  His claims about my PC containing "harmful files that my anti-virus could not pick up" were a complete fabrication.  Everything he said was misleading, alarmist or just plain false.

The icing on the cake - "Your computer is full of malicious files and that's what is causing it to run slow, I'm going to put you through to one of our Microsoft Certified Technicians to fix this up for you.  First, though, I need you to install a Microsoft Security Update..."

This "Maintenance" is a complete scam.  It's a ploy to have you install third-party software that does who-knows-what on your machine.  Apart from the obvious problems with remote access, this "security update" could include other functions that might disable your anti-virus, record internet habits, personal information or worse, keystrokes (ie, passwords).

If you receive a call from this mob:
- Take their details
- Get a "call-back" number
- Report them to consumer affairs!

I had a call from these guys today too.  I've had a few recently and i love playing with them.  I'm an IT Manager and very Windoze literate.  Like David - UK, i just got him to talk me through the event Viewer while i stood outside and had a smoke.  
I think I wasted about 20 minutes of their time - feeding them b*llsh*t all along, although they were saying this was a "free checkup".  I went through three operators in all.  None of them were real windoze users, and obviously reading from a prepared script.
But i love the suggestion of getting a URL for them and then telling them it is a phishing site, I'll use that one next time.
Yes, I'm bored at home and easily entertained.  The last fellow i spoke to didn't really understand what i meant when i explained in great detail what he should do with the 8" carrot from his fridge.  ROFL

I had a call from these guys today too.  I've had a few recently and i love playing with them.  I'm an IT Manager and very Windoze literate.  Like David - UK, i just got him to talk me through the event Viewer while i stood outside and had a smoke.  I think I wasted about 20 minutes of their time - feeding them b*llsh*t all along, although they were saying this was a "free checkup".  I went through three operators in all.  None of them were real windoze users, and obviously reading from a prepared script.But i love the suggestion of getting a URL for them and then telling them it is a phishing site, I'll use that one next time.Yes, I'm bored at home and easily entertained.  The last fellow i spoke to didn't really understand what i meant when i explained in great detail what he should do with the 8" carrot from his fridge.  ROFL

same for me 3 times in two days - 16 MayI've stalled them as a game and they gave me an Auckland Downtown address with post code- what BS!

I am in the UK and just had a similar call from a withheld number.  Being slightly suspicious i disconnected the router so the internet could not be accessed.  The very polite guy with a strong asian accent went on to show me that i had malicious files on my computer and when i told him roughly how many his reply again was "oh my god".  I then explained that i worked for a software company and would get someone at work to take a look at it he hastily ended the call.

Another in a long line, obviously. The caller actually knew my mother's last name (my father passed away last August) - now his name is no longer on the phone (mistake #1), mine is on the isp account (mistake #2), wouldn't give me their company name and just kept repeating the same thing...turn on your computer so I can fix it.  Well, while I didn't say it, I was tempted "over my dead body" - a little extreme I realize...

After telling him I only allow my brother-in-law in the computer (twice), he finally hung up.