How can I help to troubleshoot an ide-scsi / kernel issue?

[Benjamin J. Weiss]

I've got a server that's been rock-solid under RH 9 for over a year.  I just
replaced the CD-ROM with a DVD-RW so that I could back up to DVD instead of
tape.  To get it working, I put 'hda=ide-scsi' at the end of the kernel line
in grub.conf.  Now the system is unstable and reboots when certain
operations happen.  So far it's rebooted when I tried to burn the dvd using
mondoarchive and when I tried to run RealVNC.  Note that a previous version
of mondo worked fine with the tape and that VNC has been rock solid for the
last year.

The system is a dual-Xeon system with everything but the DVD burner being
scsi.

uname -a
Linux orion 2.4.20-31.9smp #1 SMP Tue Apr 13 17:40:10 EDT 2004 i686 i686
i386 GNU/Linux

/proc/scsi/scsi
Attached devices:
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: IBM      Model: DDRS-34560D      Rev: DC1B
  Type:   Direct-Access                    ANSI SCSI revision: 02
Host: scsi2 Channel: 00 Id: 02 Lun: 00
  Vendor: ARCHIVE  Model: Python 04106-XXX Rev: 7230
  Type:   Sequential-Access                ANSI SCSI revision: 02
Host: scsi3 Channel: 00 Id: 00 Lun: 00
  Vendor: MegaRAID Model: LD0 RAID5 26241R Rev: GH67
  Type:   Direct-Access                    ANSI SCSI revision: 02
Host: scsi3 Channel: 04 Id: 06 Lun: 00
  Vendor: ESG-SHV  Model: SCA HSBP M6      Rev: 0.61
  Type:   Processor                        ANSI SCSI revision: 02
Host: scsi4 Channel: 00 Id: 00 Lun: 00
  Vendor: LITE-ON  Model: DVDRW LDW-451S   Rev: GSB6
  Type:   CD-ROM                           ANSI SCSI revision: 02


I don't see anything in /var/log/messages when the reboot happened.

I'm guessing that it must have something to do with the ide-scsi emulation,
but don't know where to go from here.

Thanks!

Ben