CD rot?
How soon do CD-R/RW discs start to degrade after being etched?
Ted Constable

Jack Schofield replies: Almost everything starts to degrade as soon as it is created, so I suppose the real question is how long before the degradation makes the discs unreadable. Unfortunately, nobody knows. There are too many variables when the CD is made, including the quality of the blank disc, the power and wavelength of the laser used to write the data, the speed used and the ambient temperature. There are many more variables in the way the CD is stored, including light, temperature and humidity, the amount of handling, and any corrosive pollution in the atmosphere. Finally, discs that would happily play back on the system used to make them may prove unplayable on different equipment.

The industry consensus seems to be that CD-R discs should last for at least five to 10 years, and good quality discs stored in optimum conditions should last for 20 or 30 years, perhaps longer. Some manufacturers have produced discs that, based on accelerated ageing tests, they reckon will last for more than 200 years. On the other hand, a recent article (written in Dutch) in PC Active magazine found that some data had become unreadable after only 20 months. The conclusion seems to be that there is a lot of rubbish on the market. This is not the first such scare, but see Gordon Woolf's article for a good summary of the situation.

I've made a habit of buying the cheapest CD-R blanks available, most of them silver on both sides, but some of them Jungle-branded Monkey Media. They have been stored, unlabelled, in Case Logic loose-leaf folders that hold about 200 discs. I've checked samples and, so far, they are all readable. However, nothing of any value would be lost if they weren't. Someone more concerned about longevity might be better advised to use tested, branded media, and check samples regularly. Organisations that really need to archive lots of data should probably be using magneto-optical discs, which should last at least 100 years.

Not 3x
I have just signed up for a broadband connection with Tiscali. I could not get the heavily advertised £15.99 per month 3x faster connection on my line, but I could have the 5x faster at £19.99 per month or a 10x faster one at £26.99. Why can my telephone line take the faster, more expensive packages but not the slower, cheaper one?
Eddie Pilling

JS: Most consumer ISPs repackage BT's ADSL broadband service, with speeds that start at 512Kbps. BT usually handles the routing all the way from your house to the exchange to the ISP. Tiscali has its own network of DataStream lines, which enables it to reduce its use of the BT network, and thus offer lower speeds at lower prices. Tiscali says: "Our DataStream network is growing but lags slightly behind the BT exchange roll out. Currently we can reach approximately 70% of enabled exchanges, but expect to be close to 90% by the new year. It looks like Mr Pilling is in the 30% not yet reached by DataStream." To sum up: the technology connecting your house to the exchange is the same in all cases. However, you can only have the 3x connection if your exchange is both ADSL-enabled and Tiscali-enabled.

Just a PC
I usually replace my PC every three years. But I am sure the obsolescence affecting the PC is not a serious issue for peripherals such as the monitor, keyboard, mouse and speakers. It would surely be eco-friendly, not to mention cheaper, simply to replace the system box, but this is not possible from most companies selling PCs.
Allister Forrest

JS: I have an IBM 101-key clicky keyboard, IIyama monitor and other peripherals that are on their third PC, and so far I have had no problems getting direct suppliers to leave things out and add minus sums to their bills. However, I do this because I am fussy about what I use. It would make more economic sense to buy the package and sell on unwanted items. Otherwise, you can get fewer unwanted peripherals by buying a business PC instead of a home PC.

Backchat

· Kathryn Hampson asked for advice on how to store photos from a CompactFlash card while on a long trip, and I suggest the Archos Jukebox Multimedia 20 with CompactFlash adaptor. David Prime, Howard Baker and others pointed out that an Apple iPod could also be used, if you added the £89 Belkin Media Reader.

· Ian Cook says he had a similar problem to David France - his PC was trying to dial out - and traced it to McAfee VirusScan. "I'd configured my Update menu to Disable automatic updating, but this doesn't seem to stop the computer from attempting to connect to your ISP. During the course of my email exchange with McAfee, I got the impression that either they didn't understand the problem or were ignoring it."