Wait a second, I thought that you have used an external drive to keep an
image of your primary drive? Isn't that a case? What exact Ghost operations
did you perform? If you just crated an image of your primary disk and stored
on external hard drive, of course you would not be able to boot from it. But
if your primary disk fails or gets corrupted, you can replace it and restore
image from an external disk, recreating primary disk partitions and data.
Then you can boot from primary again and it will work.
I'm a bit confused about your precise objective, can you explain it in more
detail? (Like you did with CD-ROM problem).