The Microsoft IntelliMouse is an optical mouse, designed to work on all surfaces and to get rid of the irritating problems of gunk on the mouse wheel and so on. All surfaces, that is, except monotonous ones.

For example, don't try to use it on a glass-topped table. The poor little mouse gets all confused, as the esteemed Reg boss, Mr Linus Birtles, recently discovered.

"I plugged it in and was ready to go," he said, "When it just went mad and started going all over the place."

Naturally, we called Microsoft's press office to find out what was making our Linus' cursor behave as though it was having a seizure.

It turns out it is down to the way the mouse works out where it is. It's optical sensor takes loads of pictures every second. By comparing each image with the previous one, and looking for a pattern, the mouse can tell which direction it is moving in and how fast it is going.

Trouble is, there is no pattern on a glass surface.

The Microsoft bunnies said that it was a well-documented phenomenon, but it isn't mentioned on the outside of any of the boxes. So far we have been unable to determine whether it is on the documentation inside the box, but we will keep you posted.

It seems to be an easy mistake for the non-techie to make. And when the mouse does start moving erratically they will have no idea why and may even think it is totally kaput.

This is a mouse designed to work without a mouse mat, to eliminate the need for special surfaces. But it needs a surface that has a pattern. So, does this mean we will all need to go out and get paisley tablecloths if we have a glass surface? We hope not. ®