WIRED:FOR THE last few days, I and a group of techies at various companies in Silicon Valley have been poring over broadcasting standards, poking at Microsoft Vista, and staring at pictures of NBC's American Gladiatortelevision show.

Our aim was to find out exactly why Windows Vista, when asked to make a recording of that particular show, steadfastly refused to obey its owners. "Restrictions set by the broadcaster and/or originator of the content prohibit recording of this programme," said Vista.

But why was an operating system refusing to obey its owner and listening to NBC instead?

There was a time when personal computers were the opposite of "black boxes". Impenetrable though they were to most people, an enthusiast with enough time on their hands could tinker, examine, learn from and modify their PC: to find out how they worked, and fix them when they didn't. Like old cars, they were, at heart, comprehensible and fixable - there were user-serviceable parts inside.

These days, there's been a concerted effort by some industries to "weld shut the bonnet" of PCs.

Unlike cars, this hasn't been because the technology has somehow become too complex for mere humans to handle. Computers are almost infinitely flexible, so their designers are always struggling to make the impossibly complex possibilities of their use manageable.

No, the problem is that modern computers are a little too flexible for some people. Their endless ability to copy, record, re-edit and, crucially, redistribute expensive videos and music without the permission of the rights holders has led to a push for a Hollywood "remote control": a way that content owners can override what the owner of the computer wants it to do.

To do that, though, you have to seize control from the user. Entertainment companies in the US have tried to do this through government action: they lobbied heavily for the "broadcast flag" in the US, a special signal that would have forced computers to add digital rights management or constrain the quality of recordings made from digital television.

The US courts threw out the broadcast flag proposal because the agency that declared the rule did not have the power to do so.

After that, US Congress was lobbied to create a special law to enforce the flag, but it declined.

But the content companies have continued to put pressure on tech companies to comply with their demands. And Microsoft, it appears, has done so.

When, last week, NBC (probably accidentally) sent out a signal that said, "Don't Record This TV Show", Microsoft Vista obeyed, leaving its American Gladiator-loving users frustrated and angry.

It's still not clear how the message got from NBC, via a digital TV channel, to Vista. It may have been the signal previously known as the broadcast flag, or it may have been another signal entirely. But whatever it was, users who bought Vista weren't warned about it and many were shocked that their computer was actively overriding their wishes.

They join a long line. My detective work was on the NBC digital TV broadcast, but Canadian analog TV users have been struggling with this problem since Vista launched. It's been known for a while that Microsoft agreed to follow one particular kind of "Don't Copy" broadcast signal, called Copy Generation Management System - Analog (CGMS-A).

As the name suggests, this "Don't Copy" signal isn't for digital TV: it's for old-fashioned analog broadcasts. The signal is crammed into the same place occupied by data for teletext and subtitles - the black border above the main picture on a standard TV set.

Canadian TV doesn't use CGMS-A, however, which means that the signal is frequently sent out accidentally by broadcasters.

Vista's oversensitivity to broadcasters' wishes means that Canadian Vista users frequently find themselves locked out of their own machines' TV-recording features.

As for the NBC programme, we still don't know whether this is a bug, or a "feature" that Microsoft has agreed with broadcasters behind closed doors. One of the reasons why it's so difficult to find out is because, to create these restrictions, Microsoft has to go to some effort to prevent users finding out exactly what their machine is doing and how.

After all, if your computer says it won't record, and you can go into its innards and block the magic signal, then the broadcasters won't remain in control for long. Microsoft has found itself in the unenviable position of trying to hide its workings from its own customers.

Microsoft is clearly caught between two camps. Its customers aren't just the people who spend €150 to buy Vista; the company is also taking money and/or favours from the entertainment industry to mess with those people's computers. The more it complies with Hollywood, the angrier its users become. And the more it answers to its users, the less able it is to cut deals on content with the established media companies.

Fortunately, even if Microsoft thinks it doesn't have a choice, we do. There are (currently) no laws that say Microsoft has to obey a broadcast flag or any kind of copy-control flag. They've chosen to; and other companies like Apple and open-source projects like MythTV have decided to ignore these signals.

Now that consumers know a little about what's in that black box, they may decide to shop elsewhere.