Kevin Wells, check this first "13 - kernel - Dashboard launch fail (due to missing/bad key, or anything else that would prevent it from running) and the dashboard didn't specify why it failed.
The error it gives is because of the incompatibility between the (older) dashboard (4920) that older slayer cd installs and the new dashboard/kerne
(In detail, in the eeprom chip there is a kernel which is incompatible with the dashboard (4920) that slayer installs.)
So what do you do to fix it? You can use the dashupdate found on most new xbox games! Be sure to 1st unplug your ethernet cable before you do so!!!
Besides that, just use a good installation disc and all is fine. Use a 2.6 slayer or something similar" from here. Let us know if this works, or what you tried besides this. Good Luck.