grub boots into command line (ignores menu.lst)

[Micha Feigin <michf@post.tau.ac.il>]

After the last update grub started booting into the command line (shows grub> )
and seems to ignore menu.lst. I managed to boot by setting
kernel /boot/vmlinuz-2.6.28
boot
I then tried to reinstall the kernel hoping that it would fix grub but now when
I try the same method to boot I get the error
Invalid or unsupported executable format
The drive is formated to ext4. grub worked after that but maybe the kernel was
written in a different method now?

any ideas?

thanks