Suppose you got home from work today to discover one of your children in tears because the entire hard disk on the PC had evaporated, taking with it the entire year's coursework. Who would be to blame?

Conventional wisdom is that it's the fault of the user for failing to do backups. The question that a clever lawyer might ask a court to resolve would be: "Does the builder of the system really provide suitable tools for those backups?"

After advising a friend over the weekend, I'd be prepared to stand up in court as a witness and say: "Definitely not".

Of course, for corporations with qualified IT staff, the provision of secure, reliable backup is a matter of routine. But what about the typical home user? Is a family with a single PC, attached to the internet and able to write CDs or DVDs, really using a system you can rely on?

First, it's now accepted by the photographic industry that writable DVDs are, mostly, volatile memory. Several pros have done systematic tests, leading to the suggestion that if you use any brand other than Verbatim, and if you keep the discs longer than three years, you should assume that the data is at least partly corrupt.

Buying, configuring, testing and verifying tape backups is a complex, error-prone process for anybody who doesn't do it several times a week, professionally. It's completely absurd to expect a home user to acquire the hardware, never mind the skills, to perform staged, incremental backups, disk imaging or test restores.

And it's the matter of testing restores that is the potential nail in the PC industry's coffin: the only way to be sure you have made a restorable backup, is to restore it. So, in order for a vendor to be able to claim that it has provided backup features, it has to provide restore-verify features.

If you only have one PC, the only way to test a restore is to over-write a working machine with what might be a faulty backup, which it's hard to see any judge accepting as a sensible strategy.

Instead, home users should be encouraged to archive documents over the internet, and keep optical media only for re-installing the system and application software, and patches.