[andrewas]

Sounds like a problem with you CD-Rom - try cleaning the lens on it.

Use a standard lens cleaner, availble from anywhere. Even one designed for PSX or something will work.

Dont use it on a CD-R though, then lenses in those are different and can be destroyed more easily.

Another problem might be that you upgraded to winXP - apparently there are some problems doing this and a clean XP install works better.