Backtrack 4 grub error... help?

i installed backtrack 4 as a secondary os, but somehow it took over my external hard drive. If i turn off the computer and take the hard drive off, it gives me a grub error, but the harddrive won't work as a harddrive. Windows doesnt even recognize it there. When i wiped my external i got the same thing, and had to go through the painful process of reverting it back to backtrack 4. i know there are boot file(s) for bt4 on my pc, but i cant find them, and cant see what is inside what partition. any help would be appreciated.