FC4 mediacheck errors

[Bob Parker]

I downloaded the FC4 i386 cd isos which passed the sha1 test.
I then burnt 4 cds and sha1 tested the isos on the cdr which all 
passed the sha1 test yet again.
At install time my friend ran mediacheck on all 4 cdrs, he reports 
all failed the mediacheck.
Next I had him check the sha1sum on cd #1 which yielded the same sum 
as published by the mirrors, so what gives?

Thanks
Bob