You'll want to enable ide-scsi in lilo or grub. A search of LQ will probably explain this better than I can. That said, this is kind of a BS problem nowadays, as Mandrake should have set up your system better. Then again, they might have left it that way for people with older style systems that have it enabled and upgraded. If you search your available programs, you should be able to install a program that doesn't need this option, as most newer ones know how to play with atapi drives properly.
In fact, Linus recently posted his opinion of the ide-scsi situation, and it wasn't exactly a pleasant one. It's hack code, put in place to meet a temporary need, and never really properly addressed after that. That doesn't mean you might not have to use it, just that it should have been fixed by now.