2nd startup disk asking for name & password, but it was never setup

I have 2 startup disks in my Mac Pro Intel. One running 10.5.5 and one running 10.4.11.

I tried to startup using the 10.4 drive (which I've done many times in the past) and I got the gray screen once it opened and it crashed. Now when I try to startup using the 10.4 drive, it asks for a name and password, which it never has done before. I put in my normal name and password and it doesn't accept it. I ran Disk Utility and Disk Warrior, and neither has made any difference.

I tried resetting the password using the install disks, but it says there is no user for this disk, so there is no password to reset.

Any suggestions as to how I can get around the name and password so I can use the 10.4 drive?
Thanks.

It sounds like you may have a firmware problem with the Tiger drive. I would try reinstalling Tiger on the drive if possible. That may or may not work.

As long as you haven't set a firmware password for the machine, or a user password for the Tiger HD you shouldn't be receiving a log on message requesting name and password.

Regards.

Still got the Tiger disks? If so boot, run Repair Disk and do a clean install.

Drat chscag you beat me by one minute! Still I guess the advice is the same!!

I do have the Tiger disks, but I was hoping to not have to wipe the info from the drive.
"As long as you haven't set a firmware password for the machine, or a user password for the Tiger HD you shouldn't be receiving a log on message requesting name and password"

I know I "shouldn't get a log on message" but I am unfortunately. If there a way to bypass the log in message?

If it's a firmware issue, what are my options exactly?
Thanks for your help.