Cannot use primary IDE controller

I have a Giga-byte K8 Triton motherboard with an AMD 64 3200+ processor and an Nvidia NForce3 chipset. The mobo has two on-chip SATA controllers as well as the usual IDE controllers. The only hard drive is attached to the first SATA controller. I am running Windows XP Pro SP 2. If I attach anything at all to the primary IDE controller, even a CD-ROM drive, the BIOS recognizes it but Windows does not load. I can only use the secondary IDE controller. As far as I can tell, everything is set correctly in the BIOS. Any ideas? Thanks in advance.