|Are you doing this:|
The rest assumes you are using a CD or CD's:
Try washing the CD(s) in warm water and washing up liquid. Gently rub the underside with your thumb from outer to inner, rather than in circles. Rinse thoroughly and dry with kitchen tissue then try the restore again. I'm thinking that the CD(s) are not reading properly.
If that fails copy the disk(s) on another computer using a CD-R (not CD-RW) and burning at as low a speed as possible. Ensure the disk is finalized. Often you can get a good copy of a disk as it is a continuous process, even when it plays up when used for installing.
Always pop back and let us know the outcome - thanks
message edited by Derek