Hopefully somebody understanding the details of xbox development could help me with this one. I did some searching and tutorial reading, but couldn't really find the reason why this happens. Is it related to the way the program was developed, compiled, both, just random or what? Can something be done to the XBE to make it sign ok? And what are the effects of signed program failing the header size check, since most of them seem to execute ok? Is this the reason why returning to dashboard/launcher (when using a dashboard exploit and retail bios) from signed programs fails (error 21), or is that due to the MS dash being signed with the retail key and not the exploit key?