Well might be so that the BIOS you're using is not set up in order to boot from disc first and HDD after that.
Most bioses are unless you edit them yourself. As for guides I would recommend
http://www.teamxodus.com/modules.php...ownload&cid=13.
Also make sure to add some dummy file to AutoInstaller Deluxe. Problem is that mostly the xbox expect to see discs with more content than 1gb or so, so adding a 1gb dummyfile would be smart.
Moreover make sure to burn it to a DVD-r to be on the safe side... With the dummy file of course...
Latest update to AutoInstaller Deluxe has a lot of tools to insert dummyfiles and so on.
Recommended bios would be EvoX M8Plus Multi1.6 for 1.6/1.6b xbox's or X2 4983 for 1.0-1.5.