I tried using Hddloader, dvd2xbox and neither worked. Everytime I checked with Boxplorer, I was missing files.
First, use Boxplorer to check the number of files and size of the original disc in drive D: , then compare that to the files and size of the game on the Hard Drive.
I guarantee your missing files.
This is how I got around it.
Use Xcommander. Instead of copying all of the folders at once, copy each folder individually. Then compare the size of each folder to the original. Even using this method it did not copy the 'Voices' folder correctly the first time. There are over 2000 files in that folder alone. If it doesn't transfer a folder correctly, just delete that folder and try again. It takes a little longer, but my backup works great.