xbox freezes on xbox logo any help please?

[alabama]

hi,
i have enigmah modchip (pal) install for a couple of months and everything has worked fine backups and originals until a couple days ago it freezes on xbox logo when no disc is in the tray so i can't change xbox settings and have never changed the bios or dashboard i can still boot backups and originals.
can anyone please help with this problem
many thanks alabama