I have an older compaq (5 years) with 2 hard drives.
Drive 1 has Windews ME.
Drive 2 has Kubuntu 6.06

I replaced drive2 with another drive that also had Kubuntu 6.06.
When I go to boot I get:

"GRUB Loading stage 1.5

GRUB loading, please wait
Error 18"

Any suggestions?

Thanks

This is an excerpt from the wiki here at LQ (http://wiki.linuxquestions.org/wiki/GRUB#Error_18)

Error 18: Selected cylinder exceeds maximum supported by BIOS
This error is returned when a read is attempted at a linear block address beyond the end of the BIOS translated area. This generally happens if your disk is larger than the BIOS can handle (512MB for (E)IDE disks on older machines or larger than 8GB on others.). In more practical terms this means the BIOS is unable to start executing the kernel because the kernel is not located within the block it can access at boot up time.

This can be circumvented by creating a boot partition at the beginning of the disk that is completely within the first 1023 cylinders of the harddrive. This partition will contain the kernel.

The kernel it self does not suffer from the same limitations as the BIOS so after the BIOS has loaded the kernel the kernel will have no problem accessing the whole harddrive. Newer BIOSes will automatically translate the harddrives size in a way that it can be completely contained within the first 1023 cylinders and hence modern computers do not suffer from this problem.
The same error can happen when the BIOS detects a disk in a different way as Linux does. This can happen when changing motherboards or when moving a GRUB-bootable disk from one computer to another. If this happens, just boot with a GRUB floppy, read the C/H/S numbers from the existing partition table and manually edit the BIOS numbers to match. If using a SUSE linux and installing on VM Ware this problem is solved by creating a small partition at the very beginning of the harddisc, and mounting it as /boot.

Thanks for the prompt reply.

I also get error 21 on an another computer.

What caused all this was that, while I was away, I had 5 hard disks on 3 computers affected by some kind of power surge (or grandchild surge). Computers were off but still connected to surge protectors which were on.

i had removed windows XP from my main computer sometime ago and had Linux on both drives.. With everything out, I reinstalled XP which uses "systemCommander" and was able to get up and running on both drives.
This left me with a spare 200 g drive which I was going to replace a 60 g drive on computer #2 which I was going to replace a 20 g drive on computer #3. This is where I get the error 21.

thanks again