I hope you created a boot disk, you will need it to check your file system, sounds to me your root filesystem is corrupt or something. If you don't have a boot disk, you can goto,
http://www.ibiblio.org/pub/Linux/sys...1.7.218.tar.gz to download Tom's Root/Boot disk so you can do a disaster recovery.
Might also be a good idea to go read about the boot process howto at
http://www.linuxdoc.org.
Its either that or a reinstall.