DVD burner installation problems

I'm helping a friend add a DVD burner to his PC. We're trying to remove the CD-ROM and replace with the DVD+/-RW. But when the DVD burner is installed, the computer locks up before going into Windows. Here are his specs:

Windows 98SE
Gigabyte Technologies motherboard (GA-71XE4)
BIOS Version F9
AMD Athlon 900MHz
128MB RAM
2 Hard Drives (30GB & 4GB)
50X CD-ROM
52X CD-RW
300W Power Supply

On reboot, it suggests we go into Safe Mode, which is no problem. But when we restart from Safe Mode, it still hangs before getting to Windows. The Windows logo screen comes up but then goes back to black screen and does nothing else. When we put the CD-ROM back in, the system boots normally with no problems.

We've tried the following scenarios:
- The CD-ROM was on Secondary Master. That's where we also put the DVD burner. We made sure the jumper was set correctly.
- Moving the DVD burner to Slave and put the CD-RW as Master (still on Secondary IDE). We made sure the jumper was set correctly.
- Updating BIOS from F7 to F9 (through mfg website). There's another BIOS version - Fad (beta) - but we haven't tried that yet. The DVD shows up in BIOS as a DVD-ROM, but Windows still hangs.
- Removing CD drivers from Device Manager (in Safe Mode) and restarting. There was never a driver listed for the DVD burner.
- Replacing the DVD burner. The model is a Pacific Digital U-30213 (Lite-On is written on the drive itself). There was not another one of the same brand available, so we bought a different DVD burner (Lite-On SOHW-812S). The only change is now the black screen read something like: "Windows Protection Error. Please restart." There were no codes or further details.

Any other suggestions?

Try installing the dvd unit by itself without other cdrw on either channel to see if windows will detect it alone.