Grub installation failed, help please !

[SYNass IT Ubuntu / Linux]

Hello Ubuntu cracks and experts
Since a few days I tried many times to install Ubuntu 8.04 Beta onto a
IBM Thinkpad X31 
with only very little or no  success. All partitons for Ubuntu were new
created !

7.10 was installed on this system and was running wired and
wirelessly !!

The installation process takes a very very long time (11am to near 5pm)
and 
finally abends with red screen and Grub installation failed !!! ;-(

It says:
The 'grub' package failed to install into /target/.
without the GRUB boot loader, the installed system will not boot.

Retries loading GRUB again failed !!

Finishing the installation again brings a red screen with mentioning:
Need setup /vmlinuz kernel on partititon /dev/sda6 with root=/dev/sda6 
as kernel argument ...

Rebooting the system brings Grub Loading, please wait ...
Error 15 !?

I have absolutely NO ideas anymore how to overcome this red screen
scenario !
With Super Grub Disk I can get back to WIN on C: only and ...
... restart installation again !?!? ;-((

Your advice and suggestions are hot awaited. 
TIA and cheers, svobi