PC wont boot from the right drive

If I turn on my PC and just let it go, I get a "DISK BOOT FAILURE" message. However, if I go into my boot menu and select my primary master HD, it boots just fine. Why? I have the jumpers right, the cable right, and the BIOS is set to boot from the HDDs 1st. The primary master drive does have 2 partitions, but that shouldn't make a difference.

that's it.

Get the windowsXP cd, go into the recovery console, and type FIXBOOT

reboot, it should work. If it doesn't you may need to go into the console again and type FIXMBR