When compiling it keep in mind that the devs have to rely on it to find out the bug and fix it.
So the more informations you provide, the better it will be.
You should report the Sabayon version and architecture (x86 5.0G, x86 5.0K, x86_64 5.0K, and so on),
that you verified the checksum and are sure that the DVD is good (so you should be sure about it,
maybe trying to install it on another hard disk could be useful).
You should also provide the relevant components on your PC:
Obviously you have also to describe the problem
Here you will find how to report bugs:http://forum.sabayonlinux.org/viewtopic.php?f=57&t=16178
If you are sure that it is not your fault report it, and if it is a bug, many users will be happier
when installing Sabayon
[EDIT] by the way, username and password from your forum account should be now recognized on the tracker.