Try using the 'single' option at the LILO prompt. So if you're linux image was called 'linux' you would use
IIRC Redhat drops you straight into a root shell.
If you can't login how did you try running fsck???
You can only run fsck on a file system that isn't mounted, otherwise you might get some 'interesting' results. If you need to fsck your root filesystem you will need to boot from a disk (not one that mounts your root fs!!) and then run fsck....
HTH
Jamie...