Let's be honest, shall we: if you're reading this, you're probably the sort of person who's been where I was last week: on the recieving end of a phone call from a friend/relative/friend of a friend/friend's relative, enquiring if you could help them with a "computer problem"...

In this case, it all seemed pretty simple: the chap on the other end of the phone was rightly concerned that his second-hand Windows XP box had come without any antivirus software installed.

"No problem", I blithely replied, "just install the free edition of AVG".

And therein began the difficulty: no matter how carefully I spelled it out, the chap insisted that visiting the URL for AVG's site resulted in a 404 error. Other sites were visible, but not that one. Emailing the link produced the same result, and so, thoroughly puzzled, I agreed to a site visit the next day.

Sure enough, from both IE and Firefox, the machine would not display pages from avg.com. Further experimentation revealed that most of the other antivirus vendors' sites were similarly blocked, along with microsoft.com.

This rang faint bells with me - viruses have been blocking such sites for years - and full of confidence that I was going to be able to pull off a quick fix and look like a genius, I pulled up the C:WindowsSystem32Driversetchosts file, expecting to find a bunch of domains being redirected to What I actually found was nothing which shouldn't have been there.

So then I broke out the usual tools: Spybot, Rootkit Revealer, a manual installation of AVG via disk from another machine, HijackThis ... several hours of the machine wrongly being pronounced clean later, I remembered reading that Microsoft's OncCare sometimes managed to disinfect machines other products didn't.

I downloaded the free trial (via another machine as the Microsoft site was being blocked) and fired it up. Its first quick scan found nothing, but it also recommended installing Internet Explorer 7. I think it must have been the running of the Microsoft malicious software removal tool during the IE install which finally disinfected the machine to the point where a full OneCare scan found and removed the last of what it proclaimed to be the Conficker worm.

More Windows-savvy readers might well be saying at this point that I should have recognised the Conficker symptoms earlier. The truth is, though, that after nearly three years using Linux on my machines, it's starting to grate to have to find my way around Windows and fix knackered installs thereof, and I've been cheerfully avoiding articles about the latest threats in the Windows world, smug in the knowledge that it's not my problem any more. .. until the phone rings.

It turns out that the aspect of the infection which had me confused the most - the blocking of the AV sites - is achieved by hooking into the relevant windows API calls and tampering with their behaviour. The question has to be asked, though - why the hell is it possible for code running as a limited user - or, come to that, any user - to intercept API calls like this?

Asside from the still-woeful state of its security, Windows really does feel prehistoric to me now - no central mechanism for installing and updating software, leading to every app having its own updater (launched at startup for maximum slowdown of the machine, of course), no decent command-line, and all the nonsense of antivirus, antispyware and anti-everything-else.

It must be ten years since I started getting the phone calls from people with broken machines, and yet it's still happening. I saw the future of home computing last week, and it was a broken Windows box. Time to think the unthinkable and start installing Ubuntu as the standard remedy?