Once upon a time you try to boot Slackware, something happens and lilo is messed up. You can fix lilo really easily, all you need is CD1 of Slackware. Boot the CD and when it says boot: then you type the following:
huge.s root=/dev/hda1 noinitrd ro
Now you change huge.s to the kernel you want to boot, root= should reflect the root partition of your Slackware install. Now when you type this you have Slackware booting up with the bare.i default kernel. Now at the login prompt you login as root and either type:
That will setup Lilo from a ncurses based menu. Now you can also edit lilo's config from a file:
Either way it will fix it hopefully, Now remember man lilo has all the hex errors if you need them. When you have all that setup you now can run:
Now you must run lilo every time you change /etc/lilo.conf to update the changes, Now restart without the CD and it should work.