I have the same type of server but with no tape/zip drive. It only has a dvd and a floppy drive. I called Dell support and they suggested doing one two options:
1. change the hard drive sequence. Press F2 during boot process to go to BIOS Setup screen. Select Hard Disk Drive Sequence. You should see "System BIOS Boot Devices", (possibly)"Embedded AIC 7899" which is the SCSI Controller and "PERC 4/SC" which is the array card. (I only saw first and third one). Select "PERC 4/SC" and move it up to first position.
2. Turn off the on-board SCSI Controller. Again, go to BIOS screen, choose "Integrated Devices", inside the fist item is SCSI Controller and it is set to "On", change it to "Off".
I tried the first option first and I was still getting the error message. Used the second option and it went away.
Of course, I don't have any SCSI devices aside from the HDDs.
Hope this helps.