5.0/5.1: Installer does not find CD-ROM drive - even though it's booted off it

Hello.

I'm having difficulty with the ISO image of FreeBSD 5.1. The same 
problem also appeared in 5.0, but since 5.1 had come out, I decided to 
try that before reporting this bug.

When booting the installer off the CD-ROM and doing a Standard install, 
you first get to the stage of partitioning a hard drive.

Then you get to the stage where distributions are chosen.

After that, it wants you to choose install media. I choose CD/DVD, and 
suddenly it says:

"No CD/DVD devices found!"

This is strange, since I clearly have been able to boot from it, and 
the boot loader seems to find it.

On a whim, I also tried to choose "Floppy" for the install, but that 
didn't work either:

"No floppy devices found!"

This is more than strange. It's truly bizarre.

In the boot loader it says:

BIOS CD is cd0
BIOS drive A: is disk0
BIOS drive C: is disk1

And just before it dumps into /stand/sysinstall, I get:

ata1-master: timeout waiting for interrupt
ata1-master: ATAPI identify failed

The system is new, and has had no OS installed on it previously. I have 
upgraded the BIOS to the latest version.

Specifications:

- Microstar 865PE Neo2 LS mother board
- 3 x Intel 10/100 Desktop Adapter S cards. (Supported by the fxp 
driver)
- Cheap Geforce 4 MX based AGP graphics card
- Western Digital Special Edition 120 GB hard drive with 8 MB disk 
cache connected using the onboard ATA100 functionality. Master on the 
first IDE bus.
- Samsung CD-ROM drive connected to the second IDE bus as Master. Only 
does ATA33 with the cables I use.
- Floppy drive. :-)