Boot/Configuration error
 

Working on a RedHat 7.1 box with 2 internal SCSI drives and 1 external SCSI tape backup. All was working fine and then we moved it into a different building and installed an external Serial modem. The modem is on TTYS0 and now the backup no longer works. If i plug the backup in the PC will not boot. I get an error that says MISSING BIOS. If i unplug the backup the machine will boot and work fine. I am not sure at all as to where to begin to solve this problem as i am still new to this and i have noone to assist me in this matter. I was just kind of thrown into it. Any advice?