GRUB Loading, Error 15

Loading Ubuntu is a labor job. Then starting with it, I get this on the boot up screen

GRUB Loading Stage1.5

Grub Loading, please wait...
Error 15

I don't remember when was last time I did not hit a wall the first step out of the door. Anyhow, standard procedure is googling with this error. So I did. Unlike most of the other times, did not find something that was close enough. So I played with it myself, and found something. The root cause was as dumb as it could be, the /boot partition did not have bootable flag set.

I have a total of 4 HDDs in the system, 2 previously loaded with fc6, 2 were from my Sony Vaio. While loading Ubuntu, I did not want to lose any data, so I loaded onto a hw that only had fc6 boot partition. That was a 40GB HDD. I loaded the whole Ubuntu 8.04 system on this single HDD. For some reason, bootable flag was not set, or perhaps was not set correctly. I found 2 other partitions were set with this flag, but not the actualy boot. Changing the flag fixed problem.

Today, a year after I posted the above, I was reading something regarding GRUB, where it mentioned that GRUB stage 1.5 is to load a program that understands file systems, ext2, ext3, or rfs. It is located in the first 30 kilobytes of hard disk immediately following the MBR. So guess my original problem was that this program was loaded, but when it tried to parse the boot flag marked partition, which did NOT have GRUB stage 2 to be found and loaded, it hung.