I had the exact same problem. I think it happened when I copied Bert and Ernie into the c:\ (root) directory, since I thought they had to be there too (because the older versions of xbox.xtf and xbox book.xtf are there in addtion to those in the FONTS directory). The tutorial tells you to put bert and ernie in the same directory as xbox.xtf and xbox book.xtf, but I had two versions of each-one in the root and one in FONTS. My XBox was updated to the dashboard with a Live tab with Mechassault (PH version), but I don't have a Live account and haven't connected to the Internet with my XBox. I assumed the older .xtf files were there as a backup left by the update, but my brother's new XBox (which has the Live tab to begin with) has them too.
What I did was unlock the hard drive with hdunlock (I hope you have your password from the BACKUP directory from evox!) and accessed it in HDD Driver after doing the hex editing to remove certain instances of FATX. What I followed was the info in xboxwannabe's post in
http://forums.xbox-s...pic=74018&st=45, the one that starts with "infinte error problem - work around ! for idiots like me" When you can access the HD, you can remove the files that aren't supposed to be there, and insert other files if they should be there. For some reason, HDD Driver was showing that I had two copies of xboxdash.xbe in the c:\ directory! I deleted bert and ernie from both the c:\ directory and the FONTS directory, one of the xboxdash.xbe files, the evox files, and settings_adoc.xip. Now I'm back to the original dashboard and ready to do the exploit again.
BTW, if you use the SplinterCell exploit, do not select "settings" in the game menu. If you do, when you press the the button to go back, a "saving" notification box will show. I have no idea if this messes up the exploit, but it could.
Also, make sure you're using NTFS as your file system on your computer, since FAT32 has a limit of 4GB for file sizes. (The backup of your original XBox hard drive created by HDD Driver is a single file that is almost 8GB in size.)