Installed YDL, can't boot to OSX anymore

[David Schneider]

Help! I just installed YDL 3.0, and it's working just fine. The problem
is, I can no longer boot into OSX. When I hit 'x' at yaboot, OSX starts
to load, I get the gray screen with the Apple logo and the chasing
lines, but after a minute or so, the Apple logo changes into a circle
with a line through it and nothing else happens. 

YDL was installed on a separate, internal drive. As recommended by the
installation guide, YDL was installed on a drive that is first in the
chain and is jumpered as the master drive. That drive was the only one
checked off in the installation for being written to, so the drive with
OSX on it shouldn't have been touched at all as far as I can tell, so
I'm not sure why it won't boot.

Can anyone help me?
David