ok, boot from rescue disk, at the prompt open up your /etc/lilo.conf and check if the "root=" line points to the place where you installed lilo.
naming conventions should be:
IDE 1st master = /dev/hda
IDE 1st slave = /dev/hdb
IDE 2nd master = /dev/hdc
IDE 2nd slave = /dev/hdd
fi; 1st partition on the 2nd master is /dev/hdc1
change, and run "lilo -v -t" (verbose, test but not write), and if o.k., run "lilo -v" (verbose, install). If you're booting from rescue disk its good to run "chroot (/todir/where/root/ismounted/)" first.
If this is not it, and you're using SCSI, check first if your modules are compiled in/loading.