How to start (rescue) system from CD-ROM when File system is EXT3

I have a Linux box that uses the EXT3 file system. Now a program, that is started in /etc/init.d/rc.3 is out of control all the system resources is used up, so no login is possible. On a EXT2 filesystem, I would just boot the rescue system from the SuSE CD and change the startup script that invokes the program. On this system this is not possible. When trying to boot the system from the CD it just hangs with a black screen. What do I do. Thanks in advance Bo Jacobsen