Problem Installing FC 6

[Norm]

A friend of mine is having a challenge installing core 6.  
The disks pass the media check on both the target computer and another
computer.
Disk 1 installs properly yet when he loads disk 2 it informs him that
he has loaded the wrong disk.
He and I both downloaded from the same site about the same time and my
disks have worked so it is not the site and he is certain in both cases
he is using core 6 iso's.
Any suggestions as to what he should do next?
Norm