Grub issues on Mac Mini?

[Charles Turner <vze26m98@optonline.net>]

Hi all-

I have a new Core 2 Duo Mac Mini, and have been trying to install 
Debian Lenny on an external FireWire disk via the i386 netinst CD of 
01sept2007.

I waded through the older install documentation around the web that 
seems geared to earlier machines, have what I think is a satisfactory 
disk partition (ie MBR), but now I'm hung at boot with Grub giving me a 
"Hard Disk Error". My reading of this error is that it involves a disk 
geometry problem.

I've now checked the geometry prior to installing Grub via netinst and 
sfdisk reports:

Kernel's idea (-g): 28615 64 32
Disk geometry (-G): 3648 255 63

After grub's installed, the "geometry" command:

geometry (hd1)

returns 3648 255 63, but I still get my "Hard Disk Error" on boot.

Any thoughts on how to resolve this? I'd be happy to supply more info; 
I know I've been brief here...

Thanks! Charles Turner