Install problems, Netfinity 5k w/Adaptec RAID

[Blake Meike]

Hi,
   I'm hoping this will be easy to solve -- or at least easy to 
diagnose.  I'm new to FreeBSD, so I just don't know where to look yet.

I have a Netfinity 5k, .6Gh SMP with an Adaptec RAID.  It runs all 
manner of Linuxes just fine.  I'd like to start running BSD instead.

Install from CD fails.  If I leave APIC on, the boot into the installer 
gets as far as a message that says:

Timecounters tick every 10.000 msec

Actually, if I wait a very long time, I get one more message:

md0: Preloaded image </boot/mfsroot>  ...

If, on the other hand, I turn off APIC, I get into the installer just 
fine.  When I try to set the media to CD, however, installer tells me 
that I have no CD drives (despite the fact that is is running from 
one!)

I'd appreciate any suggestions that would help me:
1) identify the hardware that is causing the stall, so I can pull it out
2) explain to the installer where my CD drive is, with APIC off

Many thanks,
   Blake Meike