Spanning, in Ghost and other backup programs, usually means that you've filled 
one medium and need to move on to the next.  Although they appear to be 
offering you only a new file name, in fact what you need is a whole new path 
- replace the medium you're imaging _to_, and start a new file on it.

If this guess is correct, what happened is that you over-wrote the first part 
of the ghost image with the second part of the image, and now that second 
part, installed on the target drive, is not bootable, which would make sense.

Older versions of Ghost did not set the "boot" flag for a bootable partition, 
you still needed to use fdisk or the Norton equivalent to set the partition 
properly; this may still be an issue.  

You can run fdisk or some other partition utility to see the partition table.  
While you're at it, make certain that the partition sizes appear to be 
correct.  After that, you can boot to some other source (knoppix CD comes to 
mind) and check the contents of the imaged partion.  Be sure they're 
readable, see if they're all there or if maybe you did just get the second 
half of the disk.

One last thing is to check that the BIOS is pointing to the right drive - some 
allow you to change the active boot device, in which case both devices would 
have to have a partition flagged as bootable.

Good luck.

(P.S.: If the drives are identical, using dd from knoppix might be easier than 
Ghost.)