Repair Grub Files?

[Andreas Schildbach]

Hi everyone,

A second installation of Ubuntu has "stolen" my grub root.

I recently tried to set the grub root back with

 > sudo grub
 > root (hd0,0)
 > setup (hd0)

which executed without errors, but the boot configuration was currupted 
then (boot hung with just a blinking cursor).

Fortunately, I could set grub root back to (hd0,1) using a Live-CD, so 
can boot again. However:

How can I repair the grub installation on my primary Ubuntu installation?

Regards,

Andreas