Drives detecting problem

sir!
i have a intel(D815EEA) board and 733MHz processor and TWO Hard drivr both are 20GB and One hp CD-Writer.I made a primary hard drive witch has windows2000 O.S and Secondry slave has windows98 O.S and hp cd-writer made as secondry master.My problem is that when i trun on my computer Two drives detect Out of three sometimes both hard drive are detected and HP cd-writer Not detect and sometimes Hp cd-writer and primary master drive are detected and Not detect to Secondry master, sir please solve my problem with your experience.
Thank you