Halt after writing "GRUB "

[alex_holzer]

Hello,

suddenly my Gentoo box does not boot any more. It halts after Grub
(grub-2.06-r9) wrote "GRUB ". Capslock and Numlock still work.
I booted from a rescue stick and chrooted into the system. I manually
ran grub-install to the SSD and grub-mkconfig to the boot partition 
without
success.

Does grub need busybox? Portage suggested to remove busybox. So I did.

What is wrong or what is missing when the box  halts after writing "GRUB 
"?
How can I get my box boot again?

Thanks!

Alexander