that msg means your computer cannot find your DVD rom. That is cased by jumper problem, jumper are located on the back of DVD rom, check it , I believe that both your DVD rom and haddisk are both set to be master.
When you purchase your DVD rom, its default jumper setting is master. Try to set jumper on the DVD rom as slave. how to set the jumper as slave, please refer to the instruction stick on the top of DVD rom, different brand dvd rom have different setting.
