GRUB error 18

[bthepixwiz]

I just got Debian installed on my extra computer, but whenever I start it, it goes to stage 1.5, then gives me error 18, and stops. I have found out that error 18 has something to do with the boot loader and 8 gigs, but I'm not sure. I have a 30 gigabyte Seagate Barracuda, and I installed Debian using a netboot from two floppys. I can only boot from floppies, so I can't use CDs. Can anyone point me in a direction to fix this? Thanks.