Get to the multi-boot option and fails

[wnlewis]

I install Debian 8.11.0. The install finishes. I use the option key to multi-boot. I get icons of the drives that can be booted, including Linux. I select Linux. The next screen displays for about 2 seconds and has the following:
Press
l for GNU/Linux
m for Mac OS
c for CD ROM
Stage 1 boot:_
I press "l" and it takes me back to the first screen where it displays the bootable drives.
What is going on? Is the problem likely with the boot loader or with Linux?
Mac OS 10.5.8 is loaded on the first "disk" of a 300 Gb disk that I split into 3 equal parts using Disk Utility. Debian Linux is on the second "disk". The root part of Linux has over 89 Gb of space.
Thanks.

 

[Amethyst1]

Which machine is this on?

 

[wnlewis]

The Macintosh is a Sawtooth (AGP) 32 bit G4 PowerPC 3,1 with a 1.0 GHz Sonnet Encore/ST G4 7455 upgrade processor, 1 Gb of SDRAM, and a Uni North = 7 motherboard.

Two 750 Gb IDE Ultra ATA drives go through IDE to SATA adapters to an SATA card on the PCI bus.

A 300 Gb IDE Ultra ATA drive, is split into 3 equal "disks":
• The first "disk" boots to 10.5.8.
• The second "disk" is supposed to boot to Debian 8.11.0. The installation finished successfully, but the "disk" does not show on the desktop. I think it should in OS 10.4.11 or 10.5.8. It shouldn't show in 9.2.2.
• The third "disk" is empty.

A Samsung EVO 840 256 Gb SSD goes through the SATA card - this is my main drive and boots into either 10.4.11 Tiger, or 9.2.2.

When I boot with the option key, that is when I never get to either the Linux drive or the other Macintosh OS's that are available. I have to reboot, doing an option + command + P + R a few times, and then the computer will boot back to the drive and OS it had been on prior to trying to boot to Linux.