yeah, sometimes when I copy a file from CD it gets new hash
many times
CDRoller helped me to copy it right

(you can find it in emule too)
basicly what it do is read data directly from CD bypassing cache, data correction and all that stuff (it use it's own correction algorithms)
I tried few programs to do that, cdroller works best for me
just search google for 'CD data recovery'
to check a hash without reloading files in emule all the time you can use
ed2k_hash