Booting Linux with two hard drives
 

Hi
I'm a bit stuck with this problem. I have two disks in the computer (actualy it is a computer disguised as a jukebox in a bar). Both disks are in the removable casing. On the first disk is Linux and automatically starts the "jukebox application" for selecting the music at startup. The second disk is used for uploading music.
The whole process works nice on one jukebox computer, but the other gives Error 15 at startup. It says:
GRUB Loading
Error 15
Any ideas? I don't know much about Linux, so I don't know how this Grub thing works. I don't even know which distribution of Linux was preloaded.
First disk is set to master and second disk is set to slave (I also have tried other combinations: master-master, slave-master, master-cableselect, cableselect-cableselect...).
Help will be appreciated. Thank you.

You are running two different computers with the same physical disks--or with copies?

Are the computers both using similar hardware, BIOS settings, etc.?

Where did you get these drives--who setup the Linux install, programs, etc.?

The computers came with preinstalled Linux and other software. The first disk is unique for each computer, while the second was the same physical disk.
All I can say about the computer that is causing problems is, that it is older then the one with no problems. Thing is, since both computers are built in this jukebox machine, they have no keyboard attached, so I couldn't check BIOS. I guess I'll have to bring one with me next time...