Firstly, have you checked that the burn to the DVD was good? How did you burn it, and what method did you use to check that the burn is not corrupt?
Having covered that, are you saying that you get a menu similar to that shown in the first image in Visual Tour: Booting Sabayon Linux KDE4
? If so, press F5 and append the kernel parameter (a.k.a. boot cheat code) shown below to the end of the kernel boot line and hit Enter. Try each in turn, to see if you get anywhere: