Why can I only boot if i use the disc & rd=disk0s1 ? ?

[dannyw]

I installed JaS 10.5.4 on a quad core system with intel Bad Axe 2 mobo

After the install, I get a no bootable device, or a cannot find boot.phlist

 

if i F8 with the disc in and type rd=disk0s1 i suppose that loads kernels from the dvd? then it boots just fine..? why is this? what do i need to do to avoid it?

thanks so much