My problem was with the Intel dg965wh motherboard. It (and I assume some other motherboards) insists that the boot partition be flagged as "bootable."
I have 1 IDE and 4 SATA drives. It (and/or grub) "sees" the IDE drive as sde and the boot partition as /dev/sde1.
I started in recovery mode, ran "fdisk /dev/sde," entered "a" (toggle a bootable flag), "1" (partition number), and "w" (write table to disk).
ok... I did not realise you were using a i965 board. We've had exactly the same situation here :-)