The problem is that your hard drive is unlocked and therefore won't run any of the Xbox's non-modded stuff.
It has to be locked in order to do that.
It runs the Evox because Evox can run with an unlocked HDD. Profound, I know.
For one, check in Evox's menus for a HDD Lock/Unlock option. If it's not there, just make it easy on yourself and download/burn Slayerz, check the menus and find the HDD Lock/Unlock option.
If that doesn't work, make sure your hard drive is set to cable select, then try the above again.
If THAT doesn't work, ask around for how to properly install a hard drive with an exploit or whatever and/or how to fix your problem if you have one of those.
Also, the
FAQ is usually helpful.